'From Koch?' I interrupted.

I tore the letter open, and began to read.

Herr Stiffeniis, I have found the man! His name is Arnold Lutbatz and he supplies various shops in Konigsberg with wool, cotton, knitting implements, etc., for domestic use. Herr Lutbatz recognised the needle instantly from my description. The Devil's claw is used for carding tapestry wool!

I told him that I needed to know the names of persons here in town who use such instruments, and he informed me that he keeps a list of clients. He supplies private persons, as well as shops. I asked to see the list on your behalf and authority.

I am directed this instant to his lodging, and will inform you immediately of the outcome, sir, not wishing to delay the search a moment longer.

Obsequiously, Amadeus Koch.

I had the sensation of joy one feels after a long, hard winter, opening a window one morning and finding the first frail b.u.t.terfly of Spring quivering on the gla.s.s. All hope lost a minute before, my strength and determination returned with every word that I read. Each sentence sounded to my ears like a military fanfare calling me to battle once again.

'Herr Procurator?'

I had forgotten the presence of the soldier.

'An old gentleman is waiting for you downstairs, sir. He says his name's Professor Immanuel Kant.'

Chapter 26.

If Immanuel Kant had come to the Fortress, I reasoned, something serious had happened, an event of such urgency that it had obliged him to break with his usual routine. Something so simple for other men, any unforeseen change of plan const.i.tuted a sort of cataclysm for Professor Kant. Add to this the thick fog that day, a phenomenon for which he declared an unmitigated hatred, and the enormity of Kant's decision can be imagined. I ran down the stairs without delay, and out into the courtyard, where a single solid figure was barely discernible in the swirling fog. It was not the person I had been expecting.

'I'm so sorry, sir!' Johannes Odum exclaimed at the sound of my footstep. 'I had to bring him. I was left no choice.'

'Is he well?' I asked, recalling his master's agitated state of mind earlier that morning, hoping that his indisposition had not deteriorated further.

The valet looked perplexed. 'He's not been right since you left the house,' he said, his voice tense with concern. 'Then, he insisted on speaking to you again, sir. At once, he said. He...he needs that cloak he gave you.'

If I had been puzzled by the Professor's generosity that morning, I was even more surprised by this sudden volte face. If that heavy garment were so essential to his physical well-being, why had he left the warmth of his fire for the freezing cold and the rheumatic damp without waiting for me to bring it back?

'Whatever for?' I asked.

There seemed to be nothing logical or even rational in such behaviour.

'I've no idea, sir,' Johannes replied. 'He has no clear idea what he wants himself. You saw the way he was this morning. So keen to give you that garment, insistent almost...Well, he wants it back! He was so overwrought that I hitched the horse to the landau, and drove him here to calm him down. I didn't know what else to do.'

'Where is he now?' I interrupted.

'In the guard-room. But let me tell you what happened this morning...'

I felt the hand of fright clasp at my heart.

'After you left the house with Sergeant Koch,' Johannes continued, 'he sat himself down in the front parlour for the best part of an hour and stared fretfully out of the window.'

'Was he expecting visitors?'

'Oh, no, sir,' Johannes said emphatically. 'No one comes to the house these days. You are the first visitor he's had in a month or more. I took him his morning coffee at eleven o'clock, as usual, but he didn't touch it. He jumped up suddenly, saying that he urgently needed a book from Herr Flaccovius, his editor, in town. It was for his treatise, he said. He could not go on without it.'

'That mysterious treatise again,' I said, hoping that Johannes might have discovered something in the mean time.

He did not rise to the bait. 'Professor Kant ordered me to run all the way to the bookshop,' he reported instead. 'He was a bundle of nerves until I had put on my overcoat and hat, and was preparing to leave the house.'

'You left him alone?' I burst out angrily. 'Unprotected again? Is that what you are trying to tell me?'

'What else could I do, sir?' Johannes whined. 'He was safe in his own home, it was daytime, and you had sent those soldiers to watch the house. There was no danger at all. How could I refuse to go?'

'The fog is so thick, I doubt that the gendarmes can see their own noses,' I seethed, truly vexed and frustrated by the news.

'I took my own precautions, Herr Procurator,' Johannes replied in an attempt to soothe me. 'I stopped at Frau Mendelssohn's and asked her to go across and sit with him while I was out. Frau Mendelssohn lives...'

'I know who the woman is,' I broke in, recalling my chance meeting with the inquisitive old lady as I left the house that very morning.

'She's a devoted admirer of Professor Kant's,' Johannes continued. 'I told her that I was obliged to run to town on an errand, and warned her not to let my master out of her sight. I made no mention of the real motive for doing so, saying that he wasn't feeling as well as he should. Then, I rushed off to the bookshop. But when I got there, Herr Flaccovius had no idea what I was talking about. He checked his ledger and found that my master had, indeed, ordered that particular book. But Herr Flaccovius himself had delivered it into Professor Kant's hands four months ago. I returned home rapidly, thinking I had made a mistake with the t.i.tle of the volume. I expected Professor Kant to be angry, but when I told him of the mix-up, he didn't seem put out in the least.'

'We have witnessed many unpredictable and disconcerting changes of mood in him. He has a great deal on his mind with this investigation,' I said to mask my own perplexity, which was great enough. Could Herr Professor Kant be so wholly confused?

'The oddest thing comes last,' Johannes went on quickly, as if I had spoken my puzzlement aloud. 'When I saw her to the door, Frau Mendelssohn told me that my master had been in the most excellent high spirits. Not sick at all, she said. He had entertained her to a disquisition on the cause of her migraine headaches, which he attributes to an excess of magnetism in the damp air of the town. He had been so concerned about her health, he went to get some anatomical prints from his study to show her the nerves which react to humidity. Frau Mendelssohn offered to look for the ill.u.s.trations, but he insisted on searching them out for himself.'

'So, he was left alone,' I concluded, angry with myself, above all. No matter how carefully I tried to guarantee his safety, Professor Kant still managed to slip outside my net.

'Could she prevent him from retiring to his private study?' Johannes protested with a show of helplessness. 'But then...then...'

'Then, what?' I prodded.

The valet ran his hand across his brow, as if to wipe away the troubled frown that etched itself there. 'She says that she heard voices.'

'Perhaps he was murmuring as he sorted through the prints? Old people often talk to themselves without being aware of it.'

My rea.s.suring words did not sound convincing, not even to myself.

'It wasn't that, sir,' Johannes added with a sigh. 'She actually saw the visitor leaving by the garden path. The path where you and I examined those footprints in the snow last night, sir.'

I felt cold sweat break out on my brow.

Had the murderer somehow managed to set foot in the house despite the presence of the soldiers on guard? But no, Frau Mendelssohn reported that she had heard them speaking together. Would the killer have entered the house merely to speak with Kant? And even more to the point, what would Immanuel Kant have had to say to him?

'Was your master upset?'

'Not at all, sir,' Johannes replied promptly. 'As Frau Mendelssohn said herself, what possible harm could there be in Martin Lampe?'

'Martin Lampe?' I asked, recalling my brief conversation with Frau Mendelssohn that morning. 'What in heaven's name was he doing there?'

'I've no idea, sir. I could hardly ask Herr Professor.'

'Do you know Martin Lampe?' I asked.

'No, sir. I've never met him. Herr Jachmann forbade him ever to return to the house.'

'Where does he live, Johannes?'

Johannes shrugged his shoulders. 'Herr Jachmann might know, though I'd rather you didn't ask him, sir. Professor Kant certainly knows, but I have no idea myself.'

The cold was even sharper than before as night came on. The air nipped at my cold hands and at the surface of my face like an angry puppy, and I regretted my act of generosity to Sergeant Koch.

'Take me to your master,' I said. 'I have a confession to make, regarding the cloak that he so desperately wants.'

Professor Kant was seated comfortably before a huge, black, cast-iron monster of a stove in the guard-room, staring fixedly at the little blue flames that darted playfully from its open maw, a brown felt hat resting on his bony knees. In the far corner, off-duty soldiers played pinochle and smoked their long clay pipes, blissfully ignorant of the hallowed company they were keeping. Seeing him there, so old and physically frail, I felt an overwhelming urge to protect him. Such bleak surroundings seemed so unnatural for a man of his immense talents.

'Procurator Stiffeniis has come, sir,' Johannes announced.

Professor Kant jumped to his feet, spilling his hat onto the floor. He was clearly surprised to see me. 'You are well, then?' he asked, as if I had just that minute returned from a long and dangerous journey. 'But where is my cloak?' he added with that sudden shift of focus that had become so characteristic of late, and so disconcerting.

I hesitated by the door, unable to reply. Such attention to inconsequential detail robbed me of the capability to form a thought. Was Kant offended by my appearing in his presence without the gift? Or had a more general concern for the state of my health provoked the first of his two questions?

'I loaned your cloak to Sergeant Koch, sir,' I said, not quite certain if it were the correct thing to say. It was, anyhow, the truth, and the confession was made. 'The poor man was soaked to the skin,' I added by way of explanation.

Kant looked at me in silence as if my words had enchanted him. He seemed put out by the news. I had done something unforgivable, it appeared. But what wrong had I done? Such an uncompromising reaction to a simple act of kindness amazed me. It was inexplicable in the light of his own selfless generosity to me. Desperately I searched for something to say that would placate his anger, but before I could speak, he turned and smiled at me. The brainstorm had pa.s.sed. He was himself once more.

'Isn't it odd, Stiffeniis?' he said calmly.

'Sir?' I asked with circ.u.mspection.

'How circ.u.mstances alter cases. Unleash Chaos on the world and it has a boundless energy all its own.' His eyes looked straight ahead. He seemed to be staring at some solid figure, which he alone could see.

'What do you mean, sir?' I murmured, now doubly afraid of disturbing him in this perplexing state of distraction, wherever it might be leading him.

'I mean to say that the further I progress in this experiment, the more I understand that Reason operates on the surface alone. What happens beneath the surface shapes events. The Imponderable overrules us all. For the first time in my life, I can feel the invincible strength of blind Destiny.'

He turned to look at me. 'Don't you feel it, Hanno?'

He was deathly pale, and seemed more fragile than ever, his voice trailing away to a hollow whisper.

'Go home, Professor Kant,' I urged, my heart sinking within me. In that instant, I lost all hope of making my way forward. Immanuel Kant, my anchor, my compa.s.s in the storm, had gone adrift. He had left me alone on the angry, empty sea.

'I'll give you back your cloak,' I said soothingly, as if it were the answer to all his problems. 'The instant Koch returns....'

'I do not want it,' he replied gruffly, turning to his valet. 'Leave us alone, Johannes. Be gone!'

Johannes darted a worried glance at me.

'Wait next door,' I said with a nod. 'I'll call you when it is time to leave.'

As the door closed, Immanuel Kant placed his hand lightly on my arm. Leaning forward, he peered straight into my eyes. 'That woman is innocent, Stiffeniis,' he whispered.

I was amazed. 'How did you reach this conclusion, sir?' I asked. These swings of the pendulum between confusion and lucidity were disconcerting. I could do no more than follow his lead.

'Am I not correct?'

I nodded slowly. 'You are, indeed, sir. But how did you discover it?'

Kant ignored my question. 'Never mind that now. What leads you to revise your opinion of the woman, Stiffeniis? You seemed so convinced of her guilt this morning when you spoke of witchcraft.'

'She is dead,' I replied. 'Murdered before I had the chance to question her.'

Kant hunched forward in his seat. 'The Devil's claw?'

'Strangled.'

'Go on,' he said.

'Those drawings that you instructed Lublinsky to make have been invaluable, sir,' I began. 'There were footprints left at the scene of the first murder, but Anna Rostova did not leave them. I have examined her shoes. The drawings rule her out. Your method of enquiry deserves to be publicised, sir,' I continued with enthusiasm. 'As soon as this affair is successfully concluded, I plan to write a memorandum which will, I hope, explain your methods to a wider public...'

'Your opinion is most gratifying,' Kant cut in with cold sarcasm. 'Perhaps I will find some new admirers now that the old ones have deserted me. Is that what you intend?'

I thought I knew what troubled his mind. 'Without your groundbreaking work in metaphysical speculation, sir,' I said with justified vehemence, 'there would be no new generation of philosophers.'

But he would not be halted. His temper exploded, his eyes flashed, his hands waved wildly about him. 'Nutcracker Kant, the scoundrels call me, claiming that I have imprisoned the mind and the soul in a world of rigid schemes and immutable laws. My last days at the University were unbearable. So humiliating. I have never been treated in such a way before. The agony I have suffered!'

Kant's eyes gleamed with pa.s.sion. His voice was hoa.r.s.e with malice. There was no suggestion of humour in the rancorous laughter which now escaped from his lips. 'They are such fools! Romantic dreamers...they cannot imagine what I alone have been able to conceive and carry out. They will never know the beauty of...of...'

He did not finish the sentence. His eyes slid away from mine and came to rest on an imprecise point on the barrack-room wall. He was silent for quite some time, and I knelt beside his chair, afraid to speak, uncertain how to quell the high tide of bitter resentment in his breast. Suddenly, his right hand falling to rest on my sleeve, he began to speak again, his voice all but inaudible above the hissing flames of the stove.

'Can't you see the answer? Can you not, Hanno? I expected you to strike to the heart of the mystery. You're all I have left now that everyone else has deserted me. I cannot finish my work without your help...'

Clearly, I had let him down once again. But how exactly had I deluded him? What did he expect me to see that I still failed to see? Was it no more than an old man's dream of unattainable greatness? There is no quiet journey to the grave, I thought. What need had he of the good opinion of the new breed of philosophers? His genius was beyond the judgement of his peers.

'What made you decide that Anna Rostova was not the killer?' I asked, hoping to divert him from his morbid thoughts.

Kant seemed to shake himself from his torpor.

'A simple intuition, nothing more,' he said quietly. 'Would the murderer have chosen a weapon so decidedly feminine if she truly were a woman? This was a double bluff. You overlooked one important detail.' He raised his forefinger, bowed his head, and tapped the nape of his neck. 'A precise point of attack was chosen. This is the work of someone with a history of service in the Prussian army. A soldier, Stiffeniis. Such a mortal blow is used, so far as I can ascertain, only in two specific cases: for the immediate disabling of an enemy from behind, a sentry or guard who might give the alarm, or to dispatch a wounded comrade who is bound to suffer agony before dying on the battlefield.'

'A soldier, sir?' I was astonished by his perspicacity, and thought again of Lublinsky. Had I failed to see what was obvious to Kant? I let out a sigh, then all of my self-doubt came rushing out. 'Perhaps I am not the man for this task, Herr Professor. I have stumbled from one blind alley to the next. To be honest, sir, I am tempted to admit defeat and return to Lotingen.'

He stared at me as if trying to penetrate to the deepest recesses of my soul.

'You wish to resign?'

'I am not up to the challenge, sir,' I said, my voice breaking as I made the admission. 'I am lost in a maze. Every turn leads to another dead end. Something, or someone, confounds my every step. My blundering has produced more victims than the killer has claimed. I...'