Just as the category _Where_ is indicated by the spatial relations of a body to other bodies, so the category _When_ is indicated, in regard to any event or process, by its commensuration or comparison with other events or processes.

This brings us to the notion of measurement. To measure anything quant.i.tatively is to apply to it successively some quant.i.tative unit taken as a standard and to count the number of times it contains this unit. This is a process of mentally breaking up continuous quant.i.ty or _magnitude_-whether permanent or successive, _i.e._ whether extension or motion-into discontinuous quant.i.ty or _mult.i.tude_. If the measurement of permanent quant.i.ty by spatial units, and the choosing of such units, are difficult processes,(379) those of measuring successive quant.i.ty and fixing on temporal units are more difficult still. Is there any natural motion or change of a general character, whereby we can measure (externally) the time-duration of all other changes? The motions of the earth itself-on its axis and around the sun-at once suggest themselves.

And these motions form in fact the _natural_ general standard for measuring the time of all other events in the universe. All _artificial_ or mechanical devices, such as hour-gla.s.ses, watches, clocks, chronometers, etc., are simply contrivances for the more convenient application of that general and natural standard to all particular events.

It requires a little reflection to realize that all our means of measuring time-duration can only attain to _approximate_ accuracy, inasmuch as our faculties of sense perception, no matter by what devices they are aided, are so limited in range and penetration that fluctuations which fall below the _minima sensibilia_ cannot be detected. It is a necessary condition of any motion used as a standard for time-measurement that it be _regular_.

That the standard motions we actually employ are _absolutely_ regular we have no guarantee. We can test their regularity only up to the point at which our power of detecting irregularity fails.

Reflection will also show that our appreciation of time-duration is also _relative_, not absolute. It is always a comparison of one flow or current of conscious experiences with another. It is the greater regularity of astronomical motions, as compared with changes or processes experienced as taking place within ourselves, that causes us to fix on the former as the more suitable standard for the measurement of time. "There is indeed,"

writes Father Maher,(380) "a certain rhythm in many of the processes of our organic life, such as respiration, circulation, and the recurrent needs of food and sleep, which probably contribute much to our power of estimating duration.... The irregular character and varying duration of conscious states, however, soon bring home to us the unfitness of these subjective phenomena to serve as a standard measure of time." Moreover, our estimate of duration is largely dependent on the nature of the estimated experiences and of our mental att.i.tude towards them: "A period with plenty of varied incident, such as a fortnight's travel, pa.s.ses rapidly _at the time_. Whilst we are interested in each successive experience we have little spare attention to notice the duration of the experience. There is almost complete lapse of the 'enumerating' activity.

But _in retrospect_ such a period expands, because it is estimated by the number and variety of the impressions which it presents to recollection.

On the other hand a dull, monotonous, or unattractive occupation, which leaves much of our mental energy free to advert to its duration, is over-estimated whilst taking place. A couple of hours spent impatiently waiting for a train, a few days in idleness on board ship, a week confined to one's room, are often declared to const.i.tute an 'age'. But when they are past such periods, being empty of incident, shrink up into very small dimensions.... Similarly, recent intervals are exaggerated compared with equal periods more remote. Whilst as we grow older and new experiences become fewer and less impressive, each year at its close seems shorter than its predecessor."(381)

From those facts it would seem perfectly legitimate to draw this rather surprising inference: that if the rate of _all_ the changes taking place in the universe were to be suddenly and simultaneously altered in the same direction-all increased or all diminished in the same degree-and _if our powers of perception were simultaneously_ so altered as to be _readjusted to this new rate_ of change, _we could not become aware of the alteration_.(382) Supposing, for instance, that the rate of motion were doubled, the same amount of change would take place in the new day as actually took place in the old. The _external or comparative_ time of all movements-that is to say, the time of which alone we can have any appreciation-would be the same as of old. The new day would, of course, appear only half as long as the old to a mind not readjusted to the new conditions; but this would still be external time. But would the _internal_, _intrinsic_ time of each movement be unaltered? It would be the same for the readjusted mind as it was previously for the mind adjusted to these previous conditions. By an unaltered mind, however, by the Divine Mind, for instance, the same amount of motion would be seen to const.i.tute the same movement under both conditions, but to take place twice as quickly under the new conditions as it did under the old. This again, however, involves a comparison, and thus informs us merely of external or relative time. If we identify intrinsic time with _amount of change_, making the latter the measure of the former, we must conclude that alteration in the _rate_ of a motion does not alter its absolute time: and this is evident when we reflect that the very notion of a _rate_ of motion involves the comparison of the latter with some other motion.(383) Finally, we have no positive conception of the manner in which time duration is related to, or known by, the Divine Eternal Mind, which is present to all time-past, present and future.

Besides the question of the relativity of time, there are many other curious and difficult questions which arise from a consideration of time-duration, but a detailed consideration of them belongs to Cosmology. We will merely indicate a few of them.

How far is time _reversible_, at least in the case of purely mechanical movements?(384) Had time a beginning? We know from Revelation that _de facto_ it had. But can we determine by the light of reason alone whether or not it _must_ have had a beginning? The greatest philosophers are divided as to possibility or impossibility of _created_ reality existing _from all eternity_. St. Thomas has stated, as his considered opinion, that the impossibility of _creatio ab aeterno_ cannot be proved. If a series of creatures could have existed successively from all eternity, and therefore without any _first_ term of the series, this would involve the possibility of an _actually infinite mult.i.tude_ of creatures; but an actually infinite mult.i.tude of creatures, whether existing simultaneously or successively, is regarded by most philosophers as being self-contradictory and intrinsically impossible. And this although the Divine Essence, being infinitely imitable _ad extra_, and being clearly comprehended as such by the Divine Mind, contains virtually the Divine exemplars of an infinite mult.i.tude of possible creatures.

Those who defend the possibility of an actually infinite mult.i.tude of creatures consider this fact of the infinite imitability of the Divine Essence as the ground of this possibility. On the other hand, those who hold that an actually infinite mult.i.tude is self-contradictory deny the validity of this argument from possibility to actuality; and they bring forward such serious considerations and arguments in favour of their own view that this latter has been at all times much more commonly advocated than the former one.(385) Will time have an end? All the evidence of the physical sciences confirms the truth of the Christian faith that external time, as measured by the motions of the heavens, will have an end. But the internal or intrinsic time which will be the measure of the activities of immortal creatures will have no end.(386)

86. DURATION OF IMMUTABLE BEING: ETERNITY.-We have seen that _duration_ is the perseverance or continuance of a being in its existence. The duration of the Absolutely Immutable Being is a positive perfection identical with the essence itself of this Being. It is a duration without beginning, without end, without change or succession, a _permanent_ as distinct from a _successive_ duration, for it is the duration of the Necessary Being, whose essence is Pure Actuality. This duration is eternity: _an interminable duration existing all together_. _Aeternitas est interminabilis duratio tota simul existens._ This is the common definition of eternity in the proper sense of the term-absolute or necessary eternity. The word "_interminabilis_" connotes a _positive_ perfection: the exclusion of beginning and end. The word "_tota_" does not imply that the eternity has parts. The expression "_tota simul_" excludes the imperfection which is characteristic of time duration, _viz._ the _succession_ of "before" and "after". The definition given by Boetius(387) emphasizes these points, as also the indefectible character of immutable life in the Eternal Being: _Aeternitas est interminabilis vitae tota simul et prefecta possessio_.

There is, in the next place, a kind of duration which has been called _hypothetical_, _relative_, or _borrowed_ eternity: _aeternitas hypothetica_, _relativa_, _partic.i.p.ata_, also called by scholastics "_aeviternitas_". It is the duration in existence of a being that is contingent, but _of its nature incorruptible, immortal_, such as the human soul or a pure spirit. Even if such a being existed from all eternity its existence would be contingent, dependent on a real principle distinct from itself: its duration, therefore, would not be eternity in the strict sense. On the other hand, once created by G.o.d, its nature would demand conservation without end; nor could it naturally cease to exist, though absolutely speaking it could cease to exist were G.o.d to withdraw from it His conserving power. Its duration, therefore, differs from the duration of corporeal creatures which are by nature subject to change, decay, and cessation of their being. A contingent spiritual substance has by nature a beginning to its duration, or at least a duration which is not essential to it but dependent on the Necessary Being, a duration, however, which is naturally without end; whereas the duration of the corporeal being has by nature both a beginning and an end.

But philosophers are not agreed as to the nature and ground of the distinction between these two kinds of duration in contingent beings. No contingent being is self-existent, neither has any contingent being the principle of its own duration in its own essence. Just as it cannot begin to exist of itself, so neither can it continue to exist of itself. At the same time, granted that it has obtained from G.o.d actual existence, some kind or degree of duration, of continuance in that existence, seems to be naturally due to its essence. Otherwise conservation would be not only really but formally a continued creation. It is such indeed on the part of G.o.d: in G.o.d there is no variety of activity. But on the part of the creature, the preservation of the latter in existence, and therefore some degree of duration, seems to be due to it on the hypothesis that it has been brought into existence at all. The _conserving_ influence of G.o.d is to its duration in existence what the _concurring_ influence of G.o.d is to the exercise of its activities.(388) In this sense the duration of a finite being in existence is a positive perfection which we may regard as a property of its nature. But is this perfection or property of the creature which we call _duration_, (_a_) essentially _successive_ in all creatures, spiritual as well as corporeal? And (_b_) is it really identical with their actual existence (or with the reality of whatever change or actualization occurs to their existence), or it is a _mode_ of this existence or change, really distinct from the latter and conferring upon the latter the perfection of continuity or persistence?

This, at all events, is universally admitted: that _we_ cannot become aware of any duration otherwise than through our apprehension of _change_; that we have direct knowledge only of _successive_ duration; that we can conceive the _permanent_ duration of immutable reality only after the a.n.a.logy of successive duration, or as the co-existence of immutable reality with the successive duration of mutable things.

Now some philosophers identify successive duration with change, and hold that successive duration is formally the duration of things subject to change; that in so far as a being is subject to change its duration is successive, and in so far as it is free from change its duration approaches the essentially permanent duration of the Eternal, Immutable Being; that therefore the duration of corporeal, corruptible, mortal beings is _par excellence_ successive or temporal duration (_tempus_); that spiritual beings, which are substantially immutable, but nevertheless have a successive series of spiritual activities, have a sort of duration more perfect, because more permanent, than mere temporal duration, but less perfect, because less permanent, than eternal duration (_aevum_, _aeviternitas_); while the Absolutely Immutable Being alone has perfect permanent duration (_aeternitas_).(389) It is not clear whether according to this view we should distinguish between the duration of spiritual _substances_ as permanent, and that of their _acts_ as successive; or why we should not attribute _permanent_ duration to corporeal _substances_ and their _permanent accidents_, confining successive duration formally to motion or change itself. It is, moreover, implied in this view that duration is not any really distinct perfection or mode superadded to the actuality of the being that endures.

Other philosophers hold that _all_ duration of _creatures_ is _successive_; that no individual creature has a mixture of permanent and successive duration; that this successive duration is really distinct from that which endures by means of it; that it is really distinct even from the reality of change or motion itself; that it is a _real mode_ the formal function of which is to confer on the enduring reality a series of _actualities in the order of_ "_succession of posterior to prior_," a series of intrinsic _quandocationes_ (a.n.a.lagous to the intrinsic locations which their extension confers upon bodies in s.p.a.ce). These philosophers distinguish between _continuous_ or (indefinitely) _divisible_ successive duration, the (indefinitely divisible) parts of which are "past" and "future," and the present not a "part" but only an "indivisible limit" between the two parts; and _discontinuous_ or _indivisible_ successive duration, whose parts are separate and indivisible units of duration succeeding one another discontinuously: each part being a real but indivisible duration, so that besides the parts that are _past_ and _future_, the _present_ is also a _part_, which is-like an instant of time-indivisible, but which is also-unlike an instant of time-a real duration. The former kind of successive duration they ascribe to corporeal, corruptible creatures; the latter to spiritual, incorruptible creatures. This view is defended with much force and ingenuity by De San in his _Cosmologia_;(390) where also a full discussion of most of the other questions we have touched upon will be found.

CHAPTER XII. RELATION; THE RELATIVE AND THE ABSOLUTE.

87. IMPORTANCE OF THE PRESENT CATEGORY.-An a.n.a.lysis of the concept of _Relation_ will be found to have a very direct bearing both on the Theory of Being and on the Theory of Knowledge. For the human mind knowledge is embodied in the mental act of judgment, and this is an act of _comparison_, an act whereby we _relate_ or _refer_ one concept to another. The act of cognition itself involves a relation between the knowing subject and the known object, between the mind and reality.

Reality itself is understood only by our mentally recognizing or establishing relations between the objects which make up for us the whole knowable universe. This universe we apprehend not as a mult.i.tude of isolated, unconnected individuals, but as an _ordered whole_ whose parts are _inter-related_ by their mutual _co-ordinations_ and _subordinations_.

The _order_ we apprehend in the universe results from these various inter-relations whereby we apprehend it as a _system_. What we call a _law of nature_, for instance, is nothing more or less than the expression of some constant relation which we believe to exist between certain parts of this system. The study of _Relation_, therefore, belongs not merely to Logic or the Theory of Knowledge, but also to the Theory of Being, to Metaphysics. What, then, is a relation? What is the object of this mental concept which we express by the term _relation_? Are there in the known and knowable universe of our experience _real_ relations? Or are all relations _merely logical_, pure creations of our cognitive activity? Can we cla.s.sify relations, whether real or logical? What const.i.tutes a relation formally? What are the properties or characteristics of relations? These are some of the questions we must attempt to answer.

Again, there is much ambiguity, and not a little error, in the use of the terms "absolute" and "relative" in modern philosophy. To some of these sources of confusion we have referred already (5). It is a commonplace of modern philosophy, a thing accepted as unquestioned and unquestionable, that we know, and can know, only the relative. There is a true sense in this, but the true sense is not the generally accepted one.

Considering the order in which our knowledge of reality progresses it is unquestionable that we first simply perceive "things" successively, things more or less _similar_ or _dissimilar_, without realizing _in what_ they agree or differ. To realize the latter involves _reflection_ and _comparison_. Similarly we perceive "events" in succession, events some of which _depend on_ others, but without at first noting or realizing this dependence. In other words we apprehend at first _apart from their relations_, or _as absolute_, things and events which are really relative; and we do so spontaneously, without realizing even that we perceive them as absolute.

The seed needs soil and rain and sunshine for its growth; but these do not need the seed. The turbine needs the water, but the water does not need the turbine. When we realize such facts as these, _by reflection_, contrasting what is dependent with what is independent, what is like or unlike, before or after, greater or less than, other things, with what each of these is in itself, we come into conscious possession of the notion of "the relative" and oppose this to the notion of "the absolute".

What we conceive as dependent we conceive as relative; what we conceive, by negation, as independent, we conceive as absolute. Then by further observation and reflection we gradually realize that what we apprehended as independent of certain things is dependent on certain other things; that the same thing may be independent in some respects and dependent in other respects. The rain does not depend on the seed which it causes to germinate, but it does depend on the clouds. The water which turns the turbine does not depend on the turbine, but it does depend on the rain; and the rain depends on the evaporation of the waters of the ocean; and the evaporation on the solar heat; and this again on chemical and physical processes in the sun; and so on, as far as sense experience will carry us: until we realize that everything which falls directly within this sense experience is dependent and therefore relative. Similarly, the accident of quant.i.ty, in virtue of which we p.r.o.nounce one of two bodies to be _larger_ than the other, is something _absolute_ as compared with this _relation_ itself; but as compared with the substance in which it inheres, it is dependent on the latter, or _relative_ to the latter, while the substance is _absolute_, or free from dependence on it. But if substance is absolute as compared with accident, in the sense that substance is not dependent on a subject in which to inhere, but exists _in itself_, it is not absolute in the sense understood by Spinoza, in the sense of existing _of itself_, independently of any efficient cause to account for its origin (64). All the substances in the universe of our direct sense experience are contingent, dependent _ab alio_, and therefore in this sense relative, not absolute.

This is the true sense in which relativity is an essential note of the reality of all the data of the world of our sense experience. They are all contingent, or relative, or conditioned existences. And, as Kant rightly taught, this experience forces us inevitably to think of a Necessary, Absolute, Unconditioned Being, on whom these all depend. But, as can be proved in _Natural Theology_ against Kant, this concept is not a mere regulative idea of the reason, a form of thought whereby we systematize our experience: it is a concept the object of which is not merely a necessity of thought but also an objectively existing reality.(391)

But in the thought of most modern philosophers relativism, or the doctrine that "we can know only the relative," is something very different from all this. For positivists, disciples of Auguste Comte (1798-1857), it means that we can know only the phenomena which fall under the notice of our senses, and the laws of resemblance, succession, etc., according to which they occur. All "theological" quests for supra-mundane causes and reasons of these events, and all "metaphysical" quests for suprasensible forces, powers, influences, in the events themselves, as explaining or accounting for these latter, are according to this theory necessarily futile: the mind must rest content with a knowledge of the _positive facts_ of sense, and their relations. Relativism is thus another name for Positivism.

For the psychological sensism of English philosophers from Hobbes [1588-1679] and Locke [1632-1704] down to Mill [1806-73] and Bain [1818-1903] relativism means that all conscious cognition-which they tend to reduce to modes and complexes of _sensation_-must be, and can only be, a cognition of the changing, the transitional, the relative.(392) According to an extreme form of this theory the mind can apprehend only relations, but not the terms of any of these relations: it can apprehend nothing as absolute. Moreover the relations which it apprehends it creates itself. Thus all reality is reduced to a system of relations. For Mill the supreme category of real being was _Sensation_: but sensation can be only a feeling of a relation: thus the supreme category of real being would be _Relation_.(393)

But the main current of relativism is that which has issued from Kant's philosophy and worked itself out in various currents such as Spencer's Agnosticism, Hegel's Monism, and Renouvier's Neo-criticism.(394) The mind can know only what is related to it, what is present to it, what is in it; not what is apart from it, distinct from it. The mind cannot know the real nature of the extramental, nor even if there be an extramental real. Subject and object in knowledge are really one: individual minds are only self-conscious phases in the ever-evolving reality of the One Sole Actual Being.

These are but a few of the erroneous currents of modern relativism. A detailed a.n.a.lysis of them belongs to the _Theory of Knowledge_. But it may be pointed out here that they are erroneous because they have distorted and exaggerated certain profound truths concerning the scope and limits of human knowledge.

It is true that we have no positive, proper, intuitive knowledge of the Absolute Being who is the First Cause and Last End of the universe; that all our knowledge of the nature and attributes of the Infinite Being is negative, a.n.a.logical, abstractive. In a certain sense, therefore, He is above the scope of our faculties; He is Incomprehensible. But it is false to say that He is Unknowable; that our knowledge of Him, inadequate and imperfect as it is, is not genuine, real, and instructive, as far as it goes.

Again, a _distinct_ knowledge of any object implies _defining_, _limiting_, _distinguishing_, _comparing_, _relating_, _judging_; _a.n.a.lysing and synthesizing_. It implies therefore that we apprehend things _in relations_ with other things. But this supposes an antecedent, if indistinct, apprehension of the "things" themselves. Indeed we cannot help p.r.o.nouncing as simply unintelligible the contention that all knowledge is of relations, and that we can have no knowledge of things as absolute. How could we become aware of relations without being aware of the terms related? Spencer himself admits that the very reasoning whereby we establish the "relativity of knowledge" leads us inevitably to a.s.sert as necessary the existence of the non-relative, the Absolute:(395) a necessity which Kant also recognizes.

Finally, the fact that reality, in order to be known, must be present to the knowing mind-or, in other words, that knowledge itself is a relation between object and subject-in no way justifies the conclusion that we cannot know the real nature of things as they are in themselves, absolutely, but only our own subjective, mental impressions or representations of the absolute reality, in itself unknowable.(396) The obvious fact that any reality in order to be known must be related to the knowing mind, seems to be regarded by some philosophers as if it were a momentous discovery. Then, conceiving the "thing-in-itself," the absolute, as a something standing out of all relation to mind, they declare solemnly that we cannot know the absolute: a declaration which may be interpreted either as a mere truism-that we cannot know a thing without knowing it!-or as a purely gratuitous a.s.sertion, that besides the world of realities which reveal themselves to our minds there is another world of unattained and unattainable "things-in-themselves" which are as it were the _real_ realities! These philosophers have yet to show that there is anything absurd or impossible in the view that there is simply one world of realities-realities which exist absolutely in themselves apart from our apprehension of them and which in the process of cognition come into relation with our minds.(397) Moreover, if besides this world of known and knowable realities there were such a world of "transcendental" things-in-themselves as these philosophers discourse of, such a world would have very little concern for us,(398) since by definition and _ex hypothesi_ it would be _for us_ necessarily as if it were not: indeed the hypothesis of such a transcendental world is self-contradictory, for even did it exist we could not think of it.

The process of cognition has indeed its difficulties and mysteries. To examine these, to account for the possibility of truth and error, to a.n.a.lyse the grounds and define the scope and limits of human cert.i.tude, are problems for the _Theory of Knowledge_, on the domain of which we are trenching perhaps too far already in the present context. But at all events to conceive reality as absolute in the sense of being totally unrelated to mind, and then to ask: Is reality so transformed in the very process of cognition that the mind cannot possibly apprehend it or represent it as it really is?-this certainly is to misconceive and mis-state in a hopeless fashion the main problem of Epistemology.

88. a.n.a.lYSIS OF THE CONCEPT OF RELATION.-Relation is one of those ultimate concepts which does not admit of definition proper. And like other ultimate concepts it is familiar to all. Two lines, each measuring a yard, are _equal_ to each other _in length_: _equality_ is a _quant.i.tative_ relation. The number 2 is _half_ of 4, and 4 is _twice_ 2: _half_ and _double_ express each a _quant.i.tative_ relation of _inequality_. If two twin brothers are _like_ each other we have the _qualitative_ relation of _resemblance_ or _similarity_; if a negro and a European are _unlike_ each other we have the _qualitative_ relation of _dissimilarity_. The steam of the locomotive moves the train: a relation of _efficient causality_, of efficient cause to effect. The human eye is adapted to the function of seeing: a relation of _purpose_ or _finality_, of means to end. And so on.

The objective concept of relation thus establishes a _conceptual unity_ between a pair of things in the domain of some other category. Like quant.i.ty, quality, _actio_ and _pa.s.sio_, etc., it is an ultimate mode of reality as apprehended through human experience. But while the reality of the other accident-categories appertains to substances considered absolutely or in isolation from one another, the reality of this category which we call _relation_ appertains indivisibly to two (or more) together, so that when one of these is taken or considered apart from the other (or others) the relation formally disappears. Each of the other (absolute) accidents is formally "something" ("_aliquid_"; "t?"), whereas the formal function of _relation_ is to refer something "to something" else ("_ad aliquid_"; "p??? t?"). The other accidents formally inhere in a subject, "habent _esse in_ subjecto"; relation, considered formally as such, does not inhere in a subject, but gives the latter a respect, or bearing, or reference, or ordination, _to_ or _towards_ something else: "relatio dat subjecto respectum vel _esse ad_ aliquid aliud". The length of each of two lines is an _absolute_ accident of that line, but the _relation_ of equality or inequality is intelligible only of both together. Destroy one line and the relation is destroyed, though the other line retains its length absolutely and unaltered. And so of the other examples just given.

Relation, then, considered formally as such, is not an absolute accident inhering in a subject, but is a reference of this subject to some other thing, this latter being called the _term_ of the relation. Hence relation is described by the scholastics as the _ordination or respect or reference of one thing to another_: _ordo vel respectus vel habitudo unius ad aliud_. The relation of a subject to something else as term is formally not anything absolute, "_aliquid_" in that subject, but merely refers this subject to something else as term, "_ad aliquid_". Hence Aristotle's designation of relation as "p??? t?," "_ad aliquid_," "to or towards something". "We conceive as relations [p??? t?]," he says, "those things whose very ent.i.ty itself we regard as being somehow _of_ other things or _to_ another thing."(399)

To const.i.tute a relation of whatsoever kind, three elements or factors are essential: the _two extremes_ of the relation, viz. the _subject_ of the relation and the _term_ to which the subject is referred, and what is called the _foundation_, or basis, or ground, or reason, of the relation (_fundamentum_ relationis). This latter is the cause or reason on account of which the subject bears the relation to its term. It is always something absolute, in the extremes of the relation. Hence it follows that we may regard any relation in two ways, either _formally_ as the actual bond or link of connexion between the extremes, or _fundamentally_, _i.e._ as in its cause or foundation in these extremes. This is expressed technically by distinguishing between the relation _secundum esse in_ and _secundum esse ad_, _i.e._ between the absolute ent.i.ty of its foundation in the subject and the purely relative ent.i.ty in which the relation itself formally consists. Needless to say, the latter, whatever it is, does not add any _absolute ent.i.ty_ to that of either extreme. But in what does this relative ent.i.ty itself consist? Before attempting an answer to this question we must endeavour to distinguish, in the next section (89), between _purely logical_ relations and relations which are in some true sense _real_. Here we may note certain corollaries from the concept of relation as just a.n.a.lysed.

Realities of which the objective concept of relation is verified derive from this latter certain _properties_ or special characteristics. The _first_ of these is _reciprocity_: two related extremes are as such intelligible only in reference to each other: father to son, half to double, like to like, etc., and _vice versa_: _Correlativa se invicem connotant_. The _second_ is that things related to one another are collateral or concomitant in _nature_: _Correlativa sunt simul natura_: neither related extreme is as such naturally prior to the other. This is to be understood of the relation only in its _formal_ aspect, not fundamentally. Fundamentally or _materialiter_, the cause for instance is _naturally prior_ to its effect. The _third_ is that related things are concomitant _logically_, or in the order of knowledge: _Correlativa sunt simul cognitione_: a reality can be known and defined as relative to another reality only by the simultaneous cognition of both extremes of the relation.

89. LOGICAL RELATIONS.-Logical relations are _those which are created by our own thought, and which can have no being other than the being which they have in and for our thought_. That there are such relations, which are the exclusive product of our thought-activity, is universally admitted. The mind can reflect on its own direct concepts; it can compare and co-ordinate and subordinate them among themselves; it thus forms ideas of relations between those concepts, ideas which the scholastics call _reflex_ or _logical_ ideas, or "_secundae intentiones mentis_". These relations are _entia rationis_, purely logical relations. Such, for instance, are the relations of _genus_ to _species_, of predicate to subject, the relations described in Logic as the _praedicabilia_. Moreover we can compare our direct universal concepts with the individual realities they represent, and see that this feature or mode of _universality_ in the concept, its "_intentio universalitatis_" is a _logical relation_ of the concept to the reality which it represents: a logical relation, inasmuch as its _subject_ (the concept) and its _foundation_ (the _abstractness_ of the concept) are in themselves pure products of our thought-activity.

Furthermore, we are forced by the imperfection of the thought-processes whereby we apprehend reality-conception of _abstract_ ideas, _limitation_ of concepts in extension and intension, _affirmation_ and _negation_, etc.-to apprehend _conceptual_ limitations, negations, comparisons, etc., in a word, all _logical ent.i.ties_, as if they were _realities_, or after the manner of realities, _i.e._ to conceive what is really "nothing" as if it were really "something," to conceive the _non-ens_ as if it were an _ens_, to conceive it _per modum entis_ (3). And when we compare these logical ent.i.ties with one another, or with real ent.i.ties, the relations thus established by our thought are all _logical relations_. Finally, it follows from this same imperfection in our human modes of thought that we sometimes understand things only by attributing to these certain logical relations, _i.e._ relations which affect not the reality of these things, their _esse reale_, but only the mode of their presence in our minds, their _esse ideale_ (4).

In view of the distinction between logical relations and those we shall presently describe as real relations, and especially in view of the prevalent tendency in modern philosophy to regard all relations as merely logical, it would be desirable to cla.s.sify logical relations and to indicate the ways in which they are created by, or result from, our thought-processes. We know of no more satisfactory a.n.a.lysis than that accomplished by St. Thomas Aquinas in various parts of his many monumental and enduring works. In his _Commentaries on the Sentences_(400) he enumerates four ways in which logical relations arise from our thought-processes. In his _Quaestiones Disputatae_(401) he reduces these to two: some logical relations, he says, are invented by the intellect reflecting on its own concepts and are attributed to these concepts; others arise from the fact that the intellect can understand things only by relating, grouping, cla.s.sifying them, only by introducing among them an _arrangement_ or _system of relations_ through which alone it can understand them, relations which it could only erroneously ascribe to these things as they really exist, since they are only projected, as it were, into these things by the mind. Thus, though it consciously thinks of these things as so related, it deliberately abstains from a.s.serting that these relations really affect the things themselves. Now the mistake of all those philosophers, whether ancient, medieval or modern, who deny that any relations are real, seems to be that they carry this abstention too far. They contend that all relations are simply read into the reality by our thought; that none are in the reality in any true sense independently of our thought. They thus exaggerate the role of thought as a _const.i.tutive_ factor of known or experienced reality; and they often do so to such a degree that according to their philosophy human thought not merely _discovers_ or _knows_ reality but practically _const.i.tutes_ or _creates_ it: or at all events to such a degree that cognition would be mainly a process whereby reality is a.s.similated to mind and not rather a process whereby mind is a.s.similated to reality. Against all such idealist tendencies in philosophy we a.s.sert that not all relations are logical, that there are some relations which are not mere products of thought, but which are themselves real.

90. REAL RELATIONS; THEIR EXISTENCE VINDICATED.-A real relation is _one which is not a mere product of thought, but which obtains between real things independently of our thought_. For a real relation there must be (_a_) a _real_, individual _subject_; (_b_) a _real foundation_; and (_c_) a _real_, individual _term_, really distinct from the subject. If the subject of the relation, or its foundation, be not real, but a mere _ens rationis_, obviously the relation cannot be more than logical. If, moreover, the term be not a really distinct ent.i.ty from the subject, then the relation can be nothing more than a mental comparison of some thing with itself, either under the same aspect or under mentally distinct aspects. A relation is real in the fullest sense when the extremes are _mutually_ related in virtue of a foundation really existing in both.

Hence St Thomas' definition of a real relation as a _connexion between some two things in virtue of something really found in both_: _habitudo inter aliqua duo secundum aliquid realiter conveniens utrique_.(402)

Now the question: Are there in the real world, among the things which make up the universe of our experience, relations which are not merely logical, which are not a mere product of our thought?-can admit of only one reasonable answer. That there are relations which are in some true sense real and independent of our thought-activity must be apparent to everyone whose mental outlook on things has not been warped by the specious sophistries of some form or other of Subjective Idealism. For _ex professo_ refutations of Idealist theories the student must consult treatises on the _Theory of Knowledge_. A few considerations on the present point will be sufficiently convincing here.

First, then, let us appeal to the familiar examples mentioned above. Are not two lines, each a yard long, _really equal_ in length, whether we know it or not? Is not a line a yard long _really greater than_ another line a foot in length, whether we know it or not? Surely our thought does not _create_ but _discovers_ the equality or inequality. The twin brothers _really resemble_ each other, even when no one is thinking of this resemblance; the resemblance is there whether anyone adverts to it or not.

The motion of the train _really depends_ on the force of the steam; it is not our thought that produces this relation of dependence. The eye is _really_ so constructed as to perceive light, and the light is really such by nature as to arouse the sensation of vision; surely it is not our thought that produces this relation of mutual adaptation in these realities. Such relations are, therefore, in some true sense real and independent of our thought: unless indeed we are prepared to say with idealists that the lines, the brothers, the train, the steam, the eye, and the light-in a word, that not merely relations, but all accidents and substances, all realities-are mere products of thought, ideas, states of consciousness.

Again, _order_ is but a system of relations of co-ordination and subordination between really distinct things. But there is real order in the universe. And therefore there are real relations in the universe.

There is real order in the universe: In the physical universe do we not experience a real subordination of effects to causes, a real adaptation of means to ends? And in the moral universe is not this still more apparent?