The Closing of the Western Mind.

by Charles Freeman.

Introduction.

This book deals with a significant turning point in western cultural and intellectual history, when the tradition of rational thought established by the Greeks was stifled in the fourth and fifth centuries A.D. This "closing of the Western mind" did not extend to the Arab world, where translated Greek texts continued to inspire advances in astronomy, medicine and science, and so its roots must be found in developments in the Greco-Roman world of late antiquity. This book explores those developments.

Before setting out my argument, it is important to define what is meant by a tradition of rational thought. The Greeks were the first to distinguish, a.s.sess and use the distinct branch of intellectual activity we know as reasoning. By the fifth century they had grasped the principle of the deductive proof, which enabled them to make complex and irrefutable mathematical proofs. They also set out the principles of inductive reasoning, the formulation of "truths" from empirical evidence. Aristotle (384322 B.C.) used this method to make significant advances in our understanding of the natural world. These "truths," however, are always provisional. If the sun rises every day of our existence, we might a.s.sume that it will always rise, but there is no certainty of this. The Greeks recognized this as well as grasping that theories must always be the servants of facts. Describing what he has observed about the generation of bees, Aristotle notes that "the facts have not been sufficiently ascertained, and if they are ever ascertained, then we must trust perception rather than theories." Implicit in this is the thinking of cause and effect. By the fifth century we find the historian Herodotus attempting to relate what he could observe about the Nile floods with their possible causes, and this approach became rooted in the rational tradition. It was the path to a fuller understanding of the natural world and offered the possibility of effective prediction. Yet one should not idealize. In practice it is impossible to disa.s.sociate observation from the influences of the wider world. Women were seen by Greek culture to be inferior to men, and "empirical" observations could all too easily be shaped or interpreted to sustain this, as they certainly were in medicine. The astronomer Ptolemy believed the earth was at the centre of the universe, and all his observations of the planets were interpreted so as not to conflict with this model.

A successful rational tradition needs the support and understanding of the society in which it is based, and in many parts of the Greek world, this is what it received. If truth is to be effectively advanced, any finding must be open to challenge, and this means that even the greatest thinkers must never be made into figures of authority. Aristotle's colleague Theophrastus successfully queried instances of what Aristotle claimed was spontaneous generation by noticing tiny seeds Aristotle had missed. If a tradition of rational thought is to make progress, it is essential that it builds in tolerance. No authority can dictate in advance what can or cannot be believed, or there is no possibility of progress. From the philosophical point of view, it is perhaps as important that it accept the limits of what it can achieve, in those areas of knowledge where there are no basic axioms (as there are in a mathematical model, for instance) or empirical evidence from which rational thought can progress. E. R. Dodds, in his famous study The Greeks and the Irrational, The Greeks and the Irrational, notes that "honest distinction between what is knowable and what is not appears again and again in fifth-century [B.C.] thought, and is surely one of its chief glories." In short, one cannot p.r.o.nounce that a statement is true unless it can be supported by logic or empirical evidence. It followed that nothing of certainty could be said, for instance, about the G.o.ds. The problem is too complex and life is too short proclaimed the philosopher Protagoras in the fifth century. Despite these words of caution, Dodds' work reminds us that irrationality flourished in the Greek world; but perhaps one can put up with 999 irrational minds if the thousandth is an Aristotle or an Archimedes (or a Copernicus or a Newton, or, in inductive logic, a Darwin). It takes only one independent and effective rational mind to change the paradigms of understanding for the rest of humankind. notes that "honest distinction between what is knowable and what is not appears again and again in fifth-century [B.C.] thought, and is surely one of its chief glories." In short, one cannot p.r.o.nounce that a statement is true unless it can be supported by logic or empirical evidence. It followed that nothing of certainty could be said, for instance, about the G.o.ds. The problem is too complex and life is too short proclaimed the philosopher Protagoras in the fifth century. Despite these words of caution, Dodds' work reminds us that irrationality flourished in the Greek world; but perhaps one can put up with 999 irrational minds if the thousandth is an Aristotle or an Archimedes (or a Copernicus or a Newton, or, in inductive logic, a Darwin). It takes only one independent and effective rational mind to change the paradigms of understanding for the rest of humankind.

The conventional wisdom is that Greek science and mathematics petered out in the h.e.l.lenistic period (32331 B.C.), but recently scholars have shown greater appreciation of the achievements of such leading figures of the second century A.D. as Galen and Ptolemy. Galen's work on logic is being recognized so that, in the accolade of Geoffrey Lloyd, "Galen is probably unique among practising physicians in any age and culture for his professionalism also as a logician . . . conversely he is also remarkable among practising logicians for his ability in, and experience of, medical practice." The ingenuity of Ptolemy's astronomical calculations (forced on him as they were by his misconception of the universe!) was extraordinary, but one is reminded, by a recent new translation of his Geography, Geography, that he also tackled the problem of how to represent the globe on a flat surface, introduced "minutes" and "seconds" to divide up degrees and established the notion of grids of coordinates for mapping. So even in the Roman empire we are dealing with a living tradition which is making important and influential scientific advances. that he also tackled the problem of how to represent the globe on a flat surface, introduced "minutes" and "seconds" to divide up degrees and established the notion of grids of coordinates for mapping. So even in the Roman empire we are dealing with a living tradition which is making important and influential scientific advances.

There was an alternative approach to rational thought, that taken by Plato (c. 429347 B.C.). Plato believed in the reality of a world of Forms, Forms of everything from "the G.o.d" to a table, which was eternal and unchanging in contrast to the transient world here below. This world could be grasped, after an arduous intellectual journey of which only a few were capable, by means of reason. So "real" were the Forms that even the observations of the senses must be discarded if they conflicted with a Form as it was eventually discovered. "We shall approach astronomy, as we do geometry, by way of problems, and ignore what is in the sky, if we intend to get a real grasp of astronomy," as Plato put it in The Republic. The Republic. This was, of course, a challenge to the principle that facts should prevail over theories. The problem was that it was impossible to find axioms, una.s.sailable first principles, from which one could progress to a Form such as that of Beauty or "the Good," and the Platonic journey, while offering the lure of an ultimate certainty, never seemed, in practice, to be able to present a Form in terms with which all could agree. This was, of course, a challenge to the principle that facts should prevail over theories. The problem was that it was impossible to find axioms, una.s.sailable first principles, from which one could progress to a Form such as that of Beauty or "the Good," and the Platonic journey, while offering the lure of an ultimate certainty, never seemed, in practice, to be able to present a Form in terms with which all could agree.

The argument of this book is that the Greek intellectual tradition did not simply lose vigour and disappear. (Its survival and continued progress in the Arab world is testimony to that.) Rather, in the fourth and fifth century A.D. it was destroyed by the political and religious forces which made up the highly authoritarian government of the late Roman empire. There had been premonitions of this destruction in earlier Christian theology. It had been the Apostle Paul who declared war on the Greek rational tradition through his attacks on "the wisdom of the wise" and "the empty logic of the philosophers," words which were to be quoted and requoted in the centuries to come. Then came the absorption of Platonism by the early Christian theologians. It was a.s.sumed that Christian dogma could be found through the same process as Plato had advocated, in other words, through reason, and would have the same certainty as the Forms. However, as with other aspects of Platonism, it proved impossible to find secure axioms from which to start the rational argument. Scriptural texts conflicted with each other, different theological traditions had taken root in different parts of the empire, theologians disagreed whether they should discard pagan Greek philosophy or exploit it. The result, inevitably, was doctrinal confusion. Augustine was to note the existence of over eighty heresies (for which read "alternative ways of dealing with the fundamental issues of Christian doctrine"). When Constantine gave toleration to the churches in the early fourth century, he found to his dismay that Christian communities were torn by dispute. He himself did not help matters by declaring tax exemptions for Christian clergy and offering the churches immense patronage, which meant that getting the "right" version of Christian doctrine gave access not only to heaven but to vast resources on earth. By the middle of the fourth century, disputes over doctrine had degenerated into bitterness and even violence as rival bishops struggled to earn the emperor's favour and the most lucrative bishoprics. At a time of major barbarian attacks, the threat to order was so marked that it was the emperors who increasingly defined and enforced an orthodoxy, using hand-picked church councils to give themselves some theological legitimacy.

So one finds a combination of factors behind "the closing of the Western mind": the attack on Greek philosophy by Paul, the adoption of Platonism by Christian theologians and the enforcement of orthodoxy by emperors desperate to keep good order. The imposition of orthodoxy went hand in hand with a stifling of any form of independent reasoning. By the fifth century, not only has rational thought been suppressed, but there has been a subst.i.tution for it of "mystery, magic and authority," a subst.i.tution which drew heavily on irrational elements of pagan society that had never been extinguished. Pope Gregory the Great warned those with a rational turn of mind that, by looking for cause and effect in the natural world, they were ignoring the cause of all things, the will of G.o.d. This was a vital shift of perspective, and in effect a denial of the impressive intellectual advances made by the Greek philosophers.

Some who have found this argument too d.a.m.ning have stressed how it was Christians who preserved the great works of the Greek philosophers by copying them from decaying papyri, or parchment. The historian is indeed deeply indebted to the monks, the Byzantine civil servants and the Arab philosophers who preserved ancient texts, but the recording of earlier authorities is not the same as maintaining a tradition of rational thought. This can be done only if these authorities are then used as inspiration for further intellectual progress or as a bulwark against which to react. This happened in the Arab world (where, for instance, even the findings of a giant such as Galen were challenged and improved on) but not in the Byzantine empire or the Christian west. The Athenian philosopher Proclus made the last recorded astronomical observation in the ancient Greek world in A.D. 475. It was not until the sixteenth century that Copernicus-inspired by the surviving works of Ptolemy but aware that they would make more sense, and in fact would be simpler, if the sun was placed at the centre of the universe-set in hand the renewal of the scientific tradition. The struggle between religion and science had now entered a new phase, one which is beyond the scope of this book. What cannot be doubted is how effectively the rational tradition had been eradicated in the fourth and fifth centuries. The "closing of the Western mind" has been ignored for all too long. I hope this book reinvigorates debate on this turning point in European history.

I have acknowledged the many works I have drawn on for this book in the notes. In addition, my agent, Bill Hamilton, has been a consistent support during the writing of this book, and my editor at Heinemann, Ravi Mirchandani, has played a vital role in helping to set its tone and to clarify its central argument. Josine Meijer gathered the pictures together with great efficiency, and the text was meticulously copy-edited by Caroline Knight. I would also like to thank my editor at Knopf, Carol Janeway, for the enthusiasm with which she has taken on this book for the United States market. For the preparation of this book for the United States market, I am especially grateful to Serena Lehman and Ellen Feldman at Knopf, proofreaders Chuck Antony and Patrice Silverstein and indexer Max Franke.

This book is dedicated to my wife, Hilary, with my love. While I have been dealing with the complex and often stressful relationships between Christianity and pagan society in the fourth and fifth centuries, she, in her work as a psychotherapist, has been dealing with similar tensions in the minds of her clients. So our concerns have often overlapped. A tribute from Helmut Koester to his wife that I came across when reading this distinguished Swiss theologian's work seemed particularly appropriate: "It is therefore fitting that I should express here my indebtedness to her for all the patient and helpful listening to the progress of my work and for her indulgence with respect to all sorts of things around the house that I should have done rather than working on this ma.n.u.script." With the closing of this book, such duties can be evaded no longer!

Charles Freeman April 2003

Terminology and Sources.

This book draws heavily on recent research, particularly in "late antiquity." Much of this is to be found in specialist journals and expensive academic books, and the writing of this book without the help of the Cambridge University Library would have been impossible. Once again I record my thanks to its ever helpful and courteous staff.

I have recorded my sources either in the text or in notes. In addition I have used the notes to recommend further reading and to explore some topics where a digression in the text would have disrupted the flow of argument. So in the section on Alexander (chapter 4) I recommend a recent biography that reflects the state of research (note 3), give references to other sources I have used in the text (notes 4, 5, 6), and then provide a digression on the legacy of Alexander with further sources, both ancient and modern (note 7). The aim is to provide a coherent and readable narrative for the reader, with the notes available as supplementary material.

Finding the right terminology in this area is always difficult. Many of the concepts used in this book, "faith" for instance, shifted with time, and I have used the text and notes to indicate the shifts and explore the difficulties. Some terms need further mention here. The word "pagan" as used nowadays is often one of abuse, a.s.sociated with witches, hedonistic living and minority spiritual ideas. Even the most cursory knowledge of the wide variety of pagan thought and movements in the Roman empire shows that to use the term in a derogatory sense is inappropriate. The word is used in this book to describe the diverse traditions of spirituality that predated and continued to exist alongside Christianity. They included cult worship of the traditional Greek and Roman G.o.ds, mystery religions and highly sophisticated philosophical approaches to the divine. It is obvious that this very variety makes any value judgment about paganism as a whole meaningless, but it is worth saying at this stage that pagans were normally tolerant of each other and that a number of distinct spiritual allegiances could be held by an individual without impropriety. So long as public order was not threatened, an individual could follow his, or in many cases her, spiritual instincts wherever they led.

Studies of early Christianity used to stress the uniformity of Christian belief; they now stress its diversity. It is as difficult to generalize about the early Christian communities as it is to generalize about paganism, but I have used the words "church" (small c c) or "Christian communities" when appropriate. This should not imply any common agreement in doctrine or belief-such an agreement took many centuries to evolve and never became complete between the Christian communities. (In fact, one of the arguments of this book is that the debate by its very nature could not come to much in the way of agreement.) I have used "Church" (capital C) only when I quote directly from another writer who has done so, or in describing the Roman Catholic Church, which could be said to have had some understanding of its distinctiveness as the church of the west from the time of Gregory in the late sixth century. It was at about this time that the word "pope" was first used as a t.i.tle for the bishop of Rome, and I have avoided using the word for the earlier bishops on the grounds that it was not a t.i.tle they used themselves. (The question of the primacy of the bishops of Rome, actual or otherwise, over other bishops is, of course, a separate topic that I explore at appropriate points in the text.) When the emperors began to define and enforce Christian doctrine through law, I have described the doctrines they promulgated as "orthodox" (small o o), although it should be remembered that in this period an imperial definition of orthodoxy did not mean that Christian communities necessarily became "orthodox" (despite enormous financial incentives to do so). The Roman empire, even in its more authoritarian phase in late antiquity, simply did not have the power to enforce uniformity of thought. In fact, the impa.s.sioned nature of much Christian preaching may be seen as a recognition of the churches' continuing impotence in the face of Judaism, paganism and rival Christian traditions. "Orthodox" (capital O) is used to refer to the Greek-speaking churches of the east that remained true to their traditions as the popes gradually consolidated an independent western (and Latin-speaking) church in the first millennium.

A particularly difficult concept to define, at least so far as the fourth century is concerned, is "Nicene orthodoxy." The concept that G.o.d the Father and Jesus the Son were h.o.m.oousios, h.o.m.oousios, "of identical substance," was first proclaimed at the council of eastern (Greek-speaking) bishops meeting at Nicaea under the auspices of the emperor Constantine in 325. Yet, contrary to traditional interpretations of the council, recent research is stressing the difficulties the "of identical substance," was first proclaimed at the council of eastern (Greek-speaking) bishops meeting at Nicaea under the auspices of the emperor Constantine in 325. Yet, contrary to traditional interpretations of the council, recent research is stressing the difficulties the h.o.m.oousios h.o.m.oousios formula had in being accepted by the church as a whole (as the text will explain). In the eastern church it was only fully accepted as orthodoxy after the Council of Constantinople in 381, and even then there remained much opposition to the concept. However, in the western church there was always greater sympathy for the idea that Father and Son were of equal divinity, even though, as a result of the linguistic and geographical isolation of the western church, there seems to have been little awareness of the actual Nicene formulation before the 350s. I have tended to use the term "Nicene orthodoxy" rather loosely to describe those in the west who saw Father and Son as being of equal grandeur, whether they knew of or used a strictly Nicene formulation or not. formula had in being accepted by the church as a whole (as the text will explain). In the eastern church it was only fully accepted as orthodoxy after the Council of Constantinople in 381, and even then there remained much opposition to the concept. However, in the western church there was always greater sympathy for the idea that Father and Son were of equal divinity, even though, as a result of the linguistic and geographical isolation of the western church, there seems to have been little awareness of the actual Nicene formulation before the 350s. I have tended to use the term "Nicene orthodoxy" rather loosely to describe those in the west who saw Father and Son as being of equal grandeur, whether they knew of or used a strictly Nicene formulation or not.

I have acknowledged translators where possible in the notes. Most of the quoted texts from the Old and New Testaments are from the Jerusalem Bible, which I have long found the most congenial modern translation.

1.

THOMAS AQUINAS AND "THE TRIUMPH OF FAITH"

A friar in the black-and-white habit of the Dominicans sits in a niche set within an elaborate columned edifice crowned by a vault. Carved on the panels either side of him are fasces, fasces, rods bound together, a symbol of authority that reaches back through the history of ancient Rome to the Etruscans. Conventionally, as those who are attuned to the more sinister aspects of modern European history will be all too well aware, an axe is fixed within the bundle, but here it is omitted and the rods bound together, a symbol of authority that reaches back through the history of ancient Rome to the Etruscans. Conventionally, as those who are attuned to the more sinister aspects of modern European history will be all too well aware, an axe is fixed within the bundle, but here it is omitted and the fasces fasces are lit. Even in ancient times the presence of the axe was a.s.sociated with tyrannical authority, so the omission suggests a deliberate attempt to evoke an authority that is benign rather than menacing. A setting in Rome is confirmed by the views behind the imposing structure. On one side there is part of St. John Lateran, the cathedral church of Rome, fronted by an equestrian statue believed in the 1480s, the date of this fresco, to be of the emperor Constantine, its founder. are lit. Even in ancient times the presence of the axe was a.s.sociated with tyrannical authority, so the omission suggests a deliberate attempt to evoke an authority that is benign rather than menacing. A setting in Rome is confirmed by the views behind the imposing structure. On one side there is part of St. John Lateran, the cathedral church of Rome, fronted by an equestrian statue believed in the 1480s, the date of this fresco, to be of the emperor Constantine, its founder.1 On the other is the Porta Ripa Grande, the port alongside the river Tiber in Rome. The fresco itself is in the Carafa Chapel in Santa Maria Sopra Minerva, a Dominican church in the city. On the other is the Porta Ripa Grande, the port alongside the river Tiber in Rome. The fresco itself is in the Carafa Chapel in Santa Maria Sopra Minerva, a Dominican church in the city.2 Even if the fasces are not menacing, one aspect of the fresco nevertheless is. The friar crushes a scowling old man beneath his feet. The old man is a personification of evil, and he clutches a banner with the Latin inscription "Wisdom conquers evil." The friar himself is none other than the great Dominican theologian Thomas Aquinas (c. 122574). Above him in a roundel are the verses from the Book of Proverbs with which he chose to begin one of his finest works, the Even if the fasces are not menacing, one aspect of the fresco nevertheless is. The friar crushes a scowling old man beneath his feet. The old man is a personification of evil, and he clutches a banner with the Latin inscription "Wisdom conquers evil." The friar himself is none other than the great Dominican theologian Thomas Aquinas (c. 122574). Above him in a roundel are the verses from the Book of Proverbs with which he chose to begin one of his finest works, the Summa contra gentiles, Summa contra gentiles, "a summary of the case against the heretics": "For my mouth shall speak truth and wickedness is an abomination to my lips." Also above him, on panels held by "a summary of the case against the heretics": "For my mouth shall speak truth and wickedness is an abomination to my lips." Also above him, on panels held by putti, putti, appears a declaration of the importance of the revealed word of G.o.d: "The revelation of Thy words gives light; it gives understanding to the simple." The most important text, however, must be that which Thomas has selected to hold in his left hand; it is from the Apostle Paul: SAPIENTIAM SAPIENTUM PERDAM, "I will destroy the wisdom of the wise." As this book will suggest, the phrase, supported by other texts of Paul which condemn the "empty logic of the philosophers," was the opening shot in the enduring war between Christianity and science. appears a declaration of the importance of the revealed word of G.o.d: "The revelation of Thy words gives light; it gives understanding to the simple." The most important text, however, must be that which Thomas has selected to hold in his left hand; it is from the Apostle Paul: SAPIENTIAM SAPIENTUM PERDAM, "I will destroy the wisdom of the wise." As this book will suggest, the phrase, supported by other texts of Paul which condemn the "empty logic of the philosophers," was the opening shot in the enduring war between Christianity and science. 3 3 Here Thomas is in a position of authority, defending the revelatory power of G.o.d against "the wisdom of the wise." Yet this "wisdom" is allowed some place. Alongside the saint sit four further personifications, in order from the left, those of Philosophy, Theology, Grammar and Dialectic. Philosophy (largely the study of formal logic), grammar and dialectic (the art of disputation) were the first subjects of the traditional medieval curriculum. However, though they may appear at ease alongside Thomas, they are clearly subordinate to the word of G.o.d, as preliminaries that had to be mastered before any advanced study in theology, the longest and most challenging course, could begin. Theology's prominence over the others is shown here by her crown and her hand raised to heaven, as well as by her position immediately to the right of Thomas.

Below Thomas and his intellectual companions two groups of men stand back from a clutter of books and ma.n.u.scripts. A debate has been in progress, and it seems that its settlement has resulted in a disposal of discarded arguments. The reference here is to the fourth and fifth centuries, when the empire, newly if not fully Christianized, was rocked with debate over the nature of Jesus and his relationship with G.o.d. The Arians (followers of Arius) claimed that Jesus was a distinct and lower creation, divine perhaps but not fully G.o.d. At the opposite extreme, the followers of Sabellius, a Roman cleric, claimed that the G.o.dhead was one and Jesus on earth was only a temporary manifestation of that G.o.dhead, in no way distinct from it. In the fresco Arius stands on the left, a serious and thoughtful man as tradition records, wearing yellow robes. In front of him a book bearing the words of his thesis, "There was a time when the Son was not," lies condemned. Sabellius, shown as an austere Roman in a red robe, gazes down on his work with its own heretical a.s.sertion, that the Father is not to be distinguished from the Son, likewise condemned. Other heretics, including the Persian Mani (to the right of Sabellius in a furred hood), to whose sect St. Augustine belonged before his conversion to Christianity, are in the crowd. These heretics had all been subject to specific refutation by Thomas in his works. What Thomas now upholds is the final solution to the issue, the doctrine of the Trinity. G.o.d the Father, Jesus the Son and the Holy Spirit are distinct persons within a single G.o.dhead. It is a doctrine, as Thomas himself wrote in his other great work, the Summa theologiae, Summa theologiae, that cannot be upheld by reason, but only through faith. that cannot be upheld by reason, but only through faith.

The "triumph of faith," as depicted here by the Florentine painter Filippino Lippi,4 reflects the theme of this book. "Faith" is a complex concept, but whether it is trust in what cannot be seen, belief in promises made by G.o.d, essentially a declaration of loyalty or a virtue, it involves some kind of acquiescence in what cannot be proved by rational thought. What makes faith a difficult concept to explore is that it has both theological and psychological elements. At a psychological level one could argue that faith must exist in any healthy mind. If we cannot trust anyone, have any optimism that "all will be well," we cannot live full lives. Such faith will include positive responses to individuals, as evinced by those who met and travelled with Jesus. Here we cross a conceptual boundary because faith in Jesus, and in particular in the saving nature of his crucifixion and resurrection as taught by Paul, was of a different order from faith in the general sense that "all will be well." With the elaboration of Christian doctrine, faith came to mean acquiescence in the teachings of the churches-to be seen as a virtue in itself. reflects the theme of this book. "Faith" is a complex concept, but whether it is trust in what cannot be seen, belief in promises made by G.o.d, essentially a declaration of loyalty or a virtue, it involves some kind of acquiescence in what cannot be proved by rational thought. What makes faith a difficult concept to explore is that it has both theological and psychological elements. At a psychological level one could argue that faith must exist in any healthy mind. If we cannot trust anyone, have any optimism that "all will be well," we cannot live full lives. Such faith will include positive responses to individuals, as evinced by those who met and travelled with Jesus. Here we cross a conceptual boundary because faith in Jesus, and in particular in the saving nature of his crucifixion and resurrection as taught by Paul, was of a different order from faith in the general sense that "all will be well." With the elaboration of Christian doctrine, faith came to mean acquiescence in the teachings of the churches-to be seen as a virtue in itself.5 In the fourth and fifth centuries A.D., however, faith in this last sense achieved prominence over reason. The principles of empirical observation or logic were overruled in the conviction that all knowledge comes from G.o.d and even, in the writings of Augustine, that the human mind, burdened with Adam's original sin, is diminished in its ability to think for itself. For centuries any form of independent scientific thinking was suppressed. Yet, and this is the paradox of the Carafa fresco, it was actually Thomas, through reviving the works of Aristotle, who brought reason back into theology and hence into western thought. Once again it was possible for rational thought and faith to co-exist. We will meet the other Thomas, the Thomas who champions reason alongside faith, in the final chapter of this book.

We begin by returning to ancient Greece and exploring in particular how reason became established as an intellectual force in western culture. Then we can see how Christianity, under the influential banner of Paul's denunciation of Greek philosophy, began to create the barrier between science-and rational thought in general-and religion that appears to be unique to Christianity. Far from the rise of science challenging the Christian concept of G.o.d (as is often a.s.sumed by protagonists in the debate), it was Christianity that actively challenged a well-established and sophisticated tradition of scientific thinking.

2.

THE QUEST FOR CERTAINTY.

The investigation of the truth is in one way hard, in another easy. An indication of this is found in the fact that no one is able to attain the truth adequately, while, on the other hand, no one fails entirely, but everyone says something true about the nature of things, and while individually they contribute little or nothing to the truth, by the union of all a considerable amount is ama.s.sed.

ARISTOTLE1.

On his long journey home from Troy to his wife, Penelope, in Ithaca, Odysseus, the hero of Homer's Odyssey, Odyssey, was swept from his ship through the fury of Poseidon, the G.o.d of earthquakes and the sea, who had turned against him. Luckily, the G.o.ddess Leukothea, who lived in the depths of the sea, took pity on him and offered him a magic scarf that, when bound around him, would protect him, while the G.o.ddess Athena calmed the waves so that he could swim towards the sh.o.r.es of the land of the Phaeacians. In this crisis Odysseus still had to make his own decisions, in the short term at what moment he should leave the timbers of his ship and strike for sh.o.r.e. A ma.s.sive wave sent by Poseidon made the decision for him, and he found himself swimming without any support. The coast came into view, but it was rugged. Is it better, Odysseus wondered, to land where he can and risk being crushed against the cliffs by a wave, or continue onwards in his exhaustion in the hopes of finding a sandy bay? was swept from his ship through the fury of Poseidon, the G.o.d of earthquakes and the sea, who had turned against him. Luckily, the G.o.ddess Leukothea, who lived in the depths of the sea, took pity on him and offered him a magic scarf that, when bound around him, would protect him, while the G.o.ddess Athena calmed the waves so that he could swim towards the sh.o.r.es of the land of the Phaeacians. In this crisis Odysseus still had to make his own decisions, in the short term at what moment he should leave the timbers of his ship and strike for sh.o.r.e. A ma.s.sive wave sent by Poseidon made the decision for him, and he found himself swimming without any support. The coast came into view, but it was rugged. Is it better, Odysseus wondered, to land where he can and risk being crushed against the cliffs by a wave, or continue onwards in his exhaustion in the hopes of finding a sandy bay?

Odysseus' ordeal ended happily. He was washed ash.o.r.e and rescued by the beautiful Nausicaa, daughter of the Phaeacian king. He was saved by two G.o.ddesses who successfully challenged another G.o.d, Poseidon. So here is a man at the mercy of divine forces who nevertheless retained the power to think rationally and who saw rational thought as a means of bettering his chances. One can hardly say this is a revolutionary step; archaeological evidence from South African caves shows that individuals were able to provide "rational" adaptations to their changing environment (in the sense of adapting their tools) as long as 70,000 years ago. What is important is that Homer distinguishes rational thought, even at this primitive, almost instinctive level, as a mental activity, independent of the whim of the G.o.ds.2 This is the mental landscape of Greece in the eighth century or earlier-the Odyssey took its final form about 725 B.C. from much older oral traditions-but it is a world that is pa.s.sing. Odysseus is an aristocrat, a king in his land of Ithaca, where he has palaces and cattle. His wife, Penelope, though vulnerable without him, has her own status. When they are finally reunited, they enjoy each other's conversation as equals before they make together for the royal bed. Emerging is the world of the Greek city state, where, from the eighth century, one finds communities making focused settlements, typically with their own sacred s.p.a.ces and public arenas. There is a shift, probably as a result of population increase, from the "aristocratic" extravagance of cattle farming to more intensive cultivation, of olives, cereals and vines. A peasant economy emerges based on a free citizenry relying on slaves for extra labour. Women are now segregated, the aristocratic palace replaced by the enclosed home, which, unlike Penelope's palace in Ithaca, contains no allotted s.p.a.ce in which women can appear before strangers. Fighting is no longer between aristocratic heroes meeting in single combat but between ma.s.sed phalanxes of hoplites (the word comes from hoplon, hoplon, a shield), made up of the peasantry, who fight side by side with each other and overwhelm their opponents by sheer weight and determination. a shield), made up of the peasantry, who fight side by side with each other and overwhelm their opponents by sheer weight and determination.3 Population increase and political infighting encouraged settlement overseas, and the city state, or polis polis as it was known in Greek, proved eminently exportable throughout the Mediterranean. One finds the same structure, domestic areas, public meeting places and a demarcated area, the as it was known in Greek, proved eminently exportable throughout the Mediterranean. One finds the same structure, domestic areas, public meeting places and a demarcated area, the temenos, temenos, for temples and sacrificial altars, in most Greek cities. Remarkably, despite the fragmentation and extent of settlement, there remained a common sense of Greek culture, sustained by religious festivals, many of them with games, oracles and centres of pilgrimage, at which Greeks from across the Mediterranean gathered. for temples and sacrificial altars, in most Greek cities. Remarkably, despite the fragmentation and extent of settlement, there remained a common sense of Greek culture, sustained by religious festivals, many of them with games, oracles and centres of pilgrimage, at which Greeks from across the Mediterranean gathered.

The number and frequency of such festivals reflects the intensely spiritual nature of the ancient Greeks. They had a powerful sense of the sacred, often personified in G.o.ds and G.o.ddesses, elaborated in myth and celebrated at an enormous number of shrines, some natural such as caves and springs, others opulent temple complexes. Their G.o.ds remained close to them, traditionally portrayed in human form and displaying behaviour which was often all too human in its fits of jealousy and anger. Among the twelve Olympian G.o.ds the full spectrum of human life was represented, from the wild excess of emotion (Dionysus) to the calm exercise of reason (Apollo), from the l.u.s.tful enjoyment of s.e.x (Aphrodite) to virgin modesty (Artemis). Each G.o.d or G.o.ddess played a number of roles, acc.u.mulated from different traditions both inside and outside Greece. So Zeus, the father of the G.o.ds, could act as lord of the skies, as a bringer of victory, a symbol of s.e.xual potency, the upholder of rulers and the G.o.d of thunder and lightning. Alongside the Olympian G.o.ds there was a ma.s.s of lesser deities, such as Pan, the G.o.d of shepherds, and local heroes with a range of roles. Ancient Greece vibrated with spiritual presences.4 Mediation with the G.o.ds took place through prayer and sacrifice. The sacrifice was the central point of almost every ritual. An animal-an ox, sheep, goat or pig-would be presented to the G.o.ds and then killed, burnt and eaten by the community. Sacrifices were not an aberrant or cruel activity-they were a sophisticated way of dealing with the necessity of killing animals in order to eat. In fact, the rituals surrounding sacrifice suggest that the Greeks felt some unease about killing animals they had reared themselves. So the illusion was created that an animal went to its death willingly, and before the killing all present threw a handful of barley at it, as if the community as a whole was accepting responsibility for the death. At the moment of the slaughter women would utter impa.s.sioned cries, again a recognition of the seriousness of what was being done in taking life. This was a common theme in ritual, also found in Greek tragic drama, an awareness that any transition involved a loss that had to be recognized within the ritual itself. There was also a strong belief that through the maintaining of the round of rituals the city had been protected. As one Athenian citizen put it in a public debate: Our ancestors by sacrificing in accordance with the tablets of Solon [laws inst.i.tuted in the early sixth century] have handed down to us a city superior in greatness and prosperity to any other in Greece so that it behooves us to perform the same sacrifices as they did if for no other reason than that of the success which has resulted from these rites. 5 5 So, Greek religion acted as mediator of political and social tensions. Transitions could be effected through the use of ritual and difficult decisions made with the help of oracles. Even so, political life was not easy, and in the seventh and sixth centuries in particular there were continual clashes between the old aristocratic elites and the newly wealthy, who had made their money through trade, and the rising peasant cla.s.ses, increasingly conscious of their own cohesion and power. At the very worst a city would explode into civil war. Thucydides describes one case in 427 in Corfu, which saw a vicious spiral of terror and counter-terror between the ruling cla.s.ses and "democrats." In the resultant complete breakdown of order, where, as Thucydides puts it, "fanatical enthusiasm was the mark of a 'real man,' " fathers killed sons, temples were violated by the ma.s.sacre of those sheltering in them and many committed suicide rather than wait to be killed. "As for the citizens who held moderate views, they were destroyed by both the extreme parties, either for not taking part in the struggle or in envy at the possibility that they might survive."6 The most sophisticated resolution of conflicts such as these was to be made in fifth-century Athens, where all male citizens came to share in government equally, in the a.s.sembly, as jurors in the law courts and, for those aged over thirty, as administrators. Athenian democracy lasted some 140 years and, despite its exclusion of women and slaves, remains a remarkable political innovation. The most sophisticated resolution of conflicts such as these was to be made in fifth-century Athens, where all male citizens came to share in government equally, in the a.s.sembly, as jurors in the law courts and, for those aged over thirty, as administrators. Athenian democracy lasted some 140 years and, despite its exclusion of women and slaves, remains a remarkable political innovation.

It was in this resolution of internal conflicts that a remarkable intellectual development took place. It seems to have been based in an optimistic belief that there were forces that tended to good order.7 One finds such a feeling in the early sixth century B.C. in the verses of the Athenian statesman Solon, who had been charged with resolving a political crisis caused by the economic and social exploitation of a debt-ridden peasantry by the landed aristocracy. He proved to be a pragmatic statesman- it is human beings themselves, not the G.o.ds, who must bring peace and good order (the Greek word used is One finds such a feeling in the early sixth century B.C. in the verses of the Athenian statesman Solon, who had been charged with resolving a political crisis caused by the economic and social exploitation of a debt-ridden peasantry by the landed aristocracy. He proved to be a pragmatic statesman- it is human beings themselves, not the G.o.ds, who must bring peace and good order (the Greek word used is eunomie eunomie) to their cities. However, eunomie eunomie (who is personified as a daughter of Zeus) is seen as a force in her own right, even if one who works alongside mankind. In Solon's own words: (who is personified as a daughter of Zeus) is seen as a force in her own right, even if one who works alongside mankind. In Solon's own words: Eunomie makes all things well ordered and fitted and often puts chains on the unjust; she smooths the rough, puts an end to excess, blinds insolence, withers the flowers of unrighteousness, straightens crooked judgements and softens deeds of arrogance, puts an end to works of faction and to the anger of painful strife, under her all men's actions are fitting and wise.

In other words, the political world tends towards stability under the auspices of divine forces. The work of the politician lies in shifting the city's affairs into their natural groove of harmony, and he will be sustained by eunomie eunomie in achieving this ("under her all men's actions are fitting and wise"). However, remarkably and apparently uniquely to the Greek world, a further intellectual leap appears to have taken place; it was appreciated that if the city tended to good order, perhaps the universe, the cosmos, did as well. The natural world was seen to change according to rhythms, of the seasons but also of the movements of the stars, rhythms that appeared to persist in spite of the fragmented and unpredictable nature of everyday life. Only a few years later than Solon, in 585 B.C. in the Ionian city of Miletus on the coast of Asia Minor, the philosopher-scientist Thales is said to have predicted an eclipse of the sun (the eclipse did indeed take place and was independently recorded by the historian Herodotus). For Aristotle, writing some 200 years later, this was truly the moment when Greek philosophy began. An underlying order to the cosmos had been observed, and its movements were a.s.sumed to be so regular that future events could be predicted from empirical observations gathered over time. in achieving this ("under her all men's actions are fitting and wise"). However, remarkably and apparently uniquely to the Greek world, a further intellectual leap appears to have taken place; it was appreciated that if the city tended to good order, perhaps the universe, the cosmos, did as well. The natural world was seen to change according to rhythms, of the seasons but also of the movements of the stars, rhythms that appeared to persist in spite of the fragmented and unpredictable nature of everyday life. Only a few years later than Solon, in 585 B.C. in the Ionian city of Miletus on the coast of Asia Minor, the philosopher-scientist Thales is said to have predicted an eclipse of the sun (the eclipse did indeed take place and was independently recorded by the historian Herodotus). For Aristotle, writing some 200 years later, this was truly the moment when Greek philosophy began. An underlying order to the cosmos had been observed, and its movements were a.s.sumed to be so regular that future events could be predicted from empirical observations gathered over time.

This single instance was not revolutionary in itself-after all, the Egyptians had been able to work out a calendar based on the regular phases of the moon as early as 2800 B.C. Where Thales and his a.s.sociates in Miletus went further was to speculate on why the world was as it was. They began to ask major questions. What was the cosmos made of, and why did it move in the way it did? Thales himself suggested that the world may have originated in a single substance, water, and that it rested on a base of water. He was challenged by another Milesian, Anaximander. What then did the water rest on? Anaximander suggested that the apparent stability of the world arose because it was at the centre of equally powerful forces-the Boundless, he called them-that surrounded the world on all sides and from which it had been formed. Just as a city would tend towards harmony, so would the cosmos be held in balance by these surrounding forces. Another Milesian, Anaximenes, suggested that everything came from air. If steam could be condensed into water and water could be frozen into ice, it followed that a single substance could change form dramatically, and perhaps air could be condensed into solid forms. These speculations were bound to be primitive, but they did represent a new way of thinking and, moreover, one in which each thinker was able to use observation and reason to challenge his rivals. So within 150 years of Odysseus' swim to Phaeacia, rational decision-making had been transformed into something much more sophisticated and universal, what we might call science. Thinking about how the predictable rhythms of the natural world related to the observed chaos of the actual world presented, of course, a daunting challenge. But it was faced as early as 500 B.C. The brilliant Herac.l.i.tus (from the city of Ephesus, close to Miletus) believed that the underlying order (the word he used was logos, logos, which will reappear many times in this book) was sustained by continual tensions between different forces. The harmonious city, said Herac.l.i.tus, is not one in which everyone lives in peace but one among whose citizens there is constant activity and debate. "Justice," said Herac.l.i.tus, "is strife." which will reappear many times in this book) was sustained by continual tensions between different forces. The harmonious city, said Herac.l.i.tus, is not one in which everyone lives in peace but one among whose citizens there is constant activity and debate. "Justice," said Herac.l.i.tus, "is strife." 9 9 Herac.l.i.tus' insight that reasoned thought is born within the tensions of the city state is supported by modern research. Geoffrey Lloyd, who has carried out intensive explorations of the background to Greek scientific thinking, traces the origins of a systematic use of reason (without which empirical observations cannot be related to each other) to the intense political debates that raged within the Greek cities. If two factions wished to find a "just" solution to a problem without tearing apart their own city, then at some point there was likely to be a consideration of what was meant by "justice." There was an incentive to go back to first principles and attempt to define an agreed basis, some kind of axiomatic statement, from which to begin the arguments that could only take place according to rational principles if agreement was to be maintained between the opposing parties. Lloyd argues that this process can be discerned within the fragments of political debate that survive, and, crucially, it was also applied to the study of the natural world. The terminology used supports this. Lloyd shows how a word such as "witness," as used in the law courts, was the root of the word for "evidence" in scientific discourse, and how the term used for cross-examination of witnesses was adopted to describe the testing of an idea or hypothesis. He also argues that within the city the ability to argue persuasively conferred status, and that this status could be transferred into other areas of intellectual activity.10 So began the great adventure of the Greek speculative tradition. It was not a coherent process. Martin West writes: Early Greek philosophy was not a single vessel which a succession of pilots briefly commanded and tried to steer towards an agreed destination, one tacking one way, the next altering course in the light of its own perceptions. It was more like a flotilla of small craft whose navigators did not start from the same point or at the same time, nor all aim for the same goal; some went in groups, some were influenced by the movements of others, some travelled out of sight of each other.11 One important development was the distinguishing and segregation of the process of reasoning itself. The earliest surviving sustained piece of Greek philosophical reasoning comes from the first half of the fifth century, from one Parmenides from the Greek city of Elea in southern Italy. Parmenides attempts to grasp the nature of the cosmos through the use of rational thought alone (in other words, without any reliance on empirical observation). He realizes that no argument can begin unless some initial a.s.sumptions are made. His "It is and it is impossible for it not to be" is the a.s.sumption with which he starts. As Parmenides, through a G.o.ddess who is given the role of developing the argument, works towards his conclusion that all material is a single undifferentiated and unchanging ma.s.s, many controversies arise, not least because of the problems in using verbs such as "to be" in a completely new context, that of philosophical reasoning. But what Parmenides did achieve was to show that once basic a.s.sumptions and axioms have been agreed upon, reason can make its independent way to a conclusion. However, his conclusion, that it is rationally impossible to conceive of materials undergoing change, seems absurd, and it raises for the first time the question of what happens when observation and reason contradict each other.

A follower of Parmenides, Zeno (who also came from Elea), highlighted this issue in his famous paradoxes. An arrow which has been shot cannot move, says Zeno. How can this possibly be? Because, answers Zeno, it is always at a place equal to itself, and if so it must be at rest in that place. So, as it is always always at a place equal to itself, it must at a place equal to itself, it must always always be at rest. In Zeno's most famous paradox, Achilles, the fastest man on foot, will never catch up with a tortoise, because when he has reached the place where the tortoise was, the tortoise will have moved on, and when he has reached the place to which the tortoise has progressed, it will have moved on yet further. While reason can suggest that Achilles will never catch the tortoise, experience tells us that he will and that he will soon outstrip it. Observation and reason may be in conflict, and the result is a conundrum. The fact that the Greeks recognized such problems yet were not daunted by them is a measure of their growing intellectual confidence. be at rest. In Zeno's most famous paradox, Achilles, the fastest man on foot, will never catch up with a tortoise, because when he has reached the place where the tortoise was, the tortoise will have moved on, and when he has reached the place to which the tortoise has progressed, it will have moved on yet further. While reason can suggest that Achilles will never catch the tortoise, experience tells us that he will and that he will soon outstrip it. Observation and reason may be in conflict, and the result is a conundrum. The fact that the Greeks recognized such problems yet were not daunted by them is a measure of their growing intellectual confidence.

The next step, then, in this parade of intellectual innovation is to try to isolate the circ.u.mstances in which rational argument can be used to achieve certainty without being challenged by what is actually observed by our senses. Here the achievement of Aristotle was outstanding. One of Aristotle's many contributions to the definition of certainty was the introduction of the syllogism, a means by which the validity of a logical argument can be a.s.sessed.12 A syllogism is, in Aristotle's own words, "an argument in which certain things being a.s.sumed [the premises], something different from the things a.s.sumed [the conclusion] follows from necessity by the fact that they hold." What kinds of things can be "a.s.sumed"? The famous examples, although not used by Aristotle himself, are "All men are mortal" and "Socrates is a man." Both premises seem fully tenable. No one has come up with an example of a man who has not died; it is part of the condition of being human. Similarly, anyone who met Socrates would have agreed that he was a man. From these two a.s.sumptions could be drawn the conclusion: "Therefore Socrates is mortal." Aristotle went further, replacing the subjects of the a.s.sumptions with letters, so that it follows if all As are B, and C is an A, then C is B. One can subst.i.tute any suitable premises to create a valid conclusion. Aristotle goes on to explore the cases where the logic does not work. "A dog has four feet" and "A cat has four feet" are both reasonable a.s.sumptions to make from one's experience of dogs and cats in everyday life, but it does not follow that a cat is a dog, and the student in logic has to work out why this is so. "All fish are silver; a goldfish is a fish; therefore a goldfish is silver" cannot be sustained because the example of a living goldfish would itself show that the premise that "All fish are silver" is not true. A syllogism is, in Aristotle's own words, "an argument in which certain things being a.s.sumed [the premises], something different from the things a.s.sumed [the conclusion] follows from necessity by the fact that they hold." What kinds of things can be "a.s.sumed"? The famous examples, although not used by Aristotle himself, are "All men are mortal" and "Socrates is a man." Both premises seem fully tenable. No one has come up with an example of a man who has not died; it is part of the condition of being human. Similarly, anyone who met Socrates would have agreed that he was a man. From these two a.s.sumptions could be drawn the conclusion: "Therefore Socrates is mortal." Aristotle went further, replacing the subjects of the a.s.sumptions with letters, so that it follows if all As are B, and C is an A, then C is B. One can subst.i.tute any suitable premises to create a valid conclusion. Aristotle goes on to explore the cases where the logic does not work. "A dog has four feet" and "A cat has four feet" are both reasonable a.s.sumptions to make from one's experience of dogs and cats in everyday life, but it does not follow that a cat is a dog, and the student in logic has to work out why this is so. "All fish are silver; a goldfish is a fish; therefore a goldfish is silver" cannot be sustained because the example of a living goldfish would itself show that the premise that "All fish are silver" is not true.

Aristotle's syllogisms can take us only so far; their premises have to be empirically correct and relate to each other in such a way that a conclusion can be drawn from their comparison. They provide the basis for deductive argument, an argument in which a specific piece of knowledge can be drawn from knowledge already given. The development of the use of deductive proof was perhaps the greatest of the Greeks' intellectual achievements. Deductive argument had, in fact, already been used in mathematics by the Greeks before Aristotle systematized it. In an astonishing breach of conventional thinking, the Greeks conceived of abstract geometrical models from which theorems could be drawn. While the Babylonians knew that in any actual right-angled triangle the square of the hypotenuse equals the sum of the squares of the other two sides, Pythagoras' theorem generalizes to show that this must be true in any conceivable right-angled triangle, a major development both mathematically and philosophically. A deductive proof in geometry needs to begin with some incontrovertible statements, or postulates as the mathematician Euclid (writing c. 300 B.C.) named them. Euclid's postulates included the a.s.sertion that it is possible to draw a straight line from any point to any other point and that all right angles are equal to each other. His famous fifth postulate stipulated the conditions under which two straight lines will meet at some indefinite point. (It was the only one recognized as unprovable even in his own day and eventually succ.u.mbed to the a.n.a.lysis of mathematicians in the nineteenth century.) Euclid also recognized what he termed "common notions," truths that are applicable to all sciences, not merely mathematics, such as "If equals be added to equals, the wholes are equal." These postulates and "common notions" might seem self-evident, but in his Elements, Elements, one of the outstanding textbooks in history, Euclid was able to draw no less than 467 proofs from ten of them, while a later mathematician, Apollonius of Perga, was to show 487 in his one of the outstanding textbooks in history, Euclid was able to draw no less than 467 proofs from ten of them, while a later mathematician, Apollonius of Perga, was to show 487 in his Conic Sections. Conic Sections. As Robert Osserman has put it in his As Robert Osserman has put it in his Poetry of the Universe: Poetry of the Universe: In a world full of irrational beliefs and shaky speculations, the statements found in The Elements were proven true beyond a shadow of a doubt . . . The astonishing fact is that after two thousand years, n.o.body has ever found an actual "mistake" in The Elements- that is to say a statement that did not follow logically from the given a.s.sumptions.13 Later mathematicians, such as the great Archimedes (see below, p. 43), were to develop new branches and areas of mathematics from these foundations.

Dealing with the natural world is a much more complex business. It seems to be in a constant state of change-the weather changes, plants grow, wars happen, men die. As Herac.l.i.tus had observed, all is in a process of flux. Yet if an underlying order can be a.s.sumed and isolated, then some progress can be made. Such progress a.s.sumes that the G.o.ds do not disturb the workings of the world on pure whim (as they do, for instance, in prescientific thinking-if the G.o.ds can intervene to change the course of the stars or the boiling point of water at random, for instance, then nothing is predictable). The next task is to isolate cause and effect, the forces that cause things to happen in a predictable way. One finds an excellent example of this process in the Histories Histories of Herodotus (probably written in the 430s B.C.). Herodotus starts his famous survey of Egypt (book 2) with speculation on the causes of the annual Nile floods. He considers three explanations which, he tells us, others have put forward. One is that the summer winds force back the natural flow of the water, and as they die down a larger volume of water is released in compensation. This cannot be true, he notes, because the floods occur even in years when the winds do not blow. Moreover, no other rivers show this phenomenon. The second explanation is that the Nile flows from an ocean that surrounds the earth. This is not a rational explanation, says Herodotus; it can only be legend. Probably Homer or some other poet (he says somewhat scornfully) introduced the idea. The third explanation is that it is melting snows that cause the floods, but surely, says Herodotus, the further south you go the hotter it gets, as the black skins of the "natives" suggest. Snow would never fall in such regions. He goes on to provide an elaborate explanation of his own, based on the sun causing the Nile to evaporate just at a time when rainfall is low, so creating an artificially low volume of water in comparison to which the normal flow is a "flood." He misses the true cause, the heavy summer rains that run down from the mountains of Ethiopia, but even if he reaches the wrong answer, Herodotus is aware of and consciously rejects mythological explanations. He uses observation and reason to discard some explanations and formulate others. Here is the process of "scientific" thinking at work. of Herodotus (probably written in the 430s B.C.). Herodotus starts his famous survey of Egypt (book 2) with speculation on the causes of the annual Nile floods. He considers three explanations which, he tells us, others have put forward. One is that the summer winds force back the natural flow of the water, and as they die down a larger volume of water is released in compensation. This cannot be true, he notes, because the floods occur even in years when the winds do not blow. Moreover, no other rivers show this phenomenon. The second explanation is that the Nile flows from an ocean that surrounds the earth. This is not a rational explanation, says Herodotus; it can only be legend. Probably Homer or some other poet (he says somewhat scornfully) introduced the idea. The third explanation is that it is melting snows that cause the floods, but surely, says Herodotus, the further south you go the hotter it gets, as the black skins of the "natives" suggest. Snow would never fall in such regions. He goes on to provide an elaborate explanation of his own, based on the sun causing the Nile to evaporate just at a time when rainfall is low, so creating an artificially low volume of water in comparison to which the normal flow is a "flood." He misses the true cause, the heavy summer rains that run down from the mountains of Ethiopia, but even if he reac