Some years ago I resolved to research the lives and careers of a number of doctors I had known when I was a child. I was in relatively good health at the time, and that fact enabled me to view the individuals with a certain distance, far removed from the terror with which I had regarded them as a boy.

I studied the contents of the personal archives of Professor S, a history scholar and a man of great intellectual and moral honesty. He had decided, a long time before, to conduct research along the same lines as mine, but with a quite different aim. During our brief conversation seven years ago, I was able to establish that for Professor S, medicine, and indeed science in general – notwithstanding the huge advances made in the last few decades – represented ‘the darkness born of the light’. I well remember his exact words, and those of his hasty correction: ‘or rather, the light that feeds on the darkness’.

The voice of Professor S was very hoarse at the time and I had to strain to hear him. But my discomfort was nothing against the compassion he showed towards those modest doctors who, in the course of their careers, had been forced to try their strength against ‘mysteries bigger than themselves’.

He lent me the papers relating to the case described in the pages that follow. I have summarized them as best I could.

One winter morning Doctor Abraham Fleischmann realized that he could no longer remember the name of his best friend. He was alone in the house; his housekeeper only came in on weekdays, and his old friend Lea was confined to her bed with a severe migraine. In the night the doctor had dreamed about an earthquake, and after that about a meeting with a curious individual whose hair shone with brilliantine and whom everyone referred to as the Spirit of the Times. In the morning when he awoke his thoughts turned to his friend, a television announcer and a master of chess.

He had never written down his friend’s telephone number in his leather-bound address book, nor stored it in the memory of the personal computer that was a present from his cousin in Connecticut; he phoned his friend every day. But in November the friend had left for a four-week holiday, and between then and now his telephone number had erased itself from Doctor Fleischmann’s memory.

He went to look it up in the telephone directory – but under what name? For more than ten minutes the doctor was unable to recall either the first or the last name of Isaac Rosenwasser. ‘I’ll just see if I’m still asleep,’ he said, pinching his arm. ‘Of course, this might be only a dream too,’ he went on, loudly. ‘Dreaming of pinching oneself; what nonsense,’ he thought.

Fleischmann set great store by the discipline, by the almost stately formality of his own thought processes. He was a person who managed to find the appropriate saying for every occasion, and his patients, as well as praising him as a great doctor, considered him a veritable master of life.

‘What is his name?’ he persisted to himself that cold morning. ‘It’s here on the tip of my tongue, and yet I cannot remember it. This is ridiculous – we grew up together!’

Before long his indignation turned to fear, timidly at first, then more violent. ‘What if it’s the beginning of a disease?’ He banished the thought. ‘Don’t go assuming the worst just because of a simple memory lapse. The synapses of two neurones got a bit mixed up. An ion of sodium or potassium missed the boat between two cells in the cerebral cortex.’

He got out of bed and did a few gymnastic exercises. At fifty-five he was in the prime of life, fit enough on the ski slopes to leave many younger men behind. He had more than one lover among the younger, more forward women of the Eighth District, even among the girls. He telephoned one of them, and during their afternoon encounter in a tiny apartment he was able to forget his disagreeable case of amnesia.

But five days later Doctor Fleischmann was surprised to find himself searching at length and in vain for the word ‘injection’: the sounds escaped him. He stood speechless before his patient. The word’s meaning was circulating in the convolutions of his brain but its sound would not come. After twenty long seconds the doctor found it again in his acoustic memory. He wrote the patient a prescription for injections of vitamin B12 to be taken once a day for a week.

‘I’m so tired!’ Fleischmann exclaimed loudly, as soon as the patient had closed the door behind him. ‘Perhaps I too ought to take a cure for my nerves. I have too many commitments. I need to sort things out.’ At that stage it hadn’t occurred to him that he might possibly be dealing with an organic illness. He was sure in himself of the machinery of his body; his daily performances, at sport and in bed, convinced him that it was functioning perfectly.

He wasted no time in attempting to reassure himself that all was well: in an exercise that, while a little childish, was quite typical of him, he repeated to himself a hundred times the word ‘injection’, each time scrutinizing every thought and mental association that passed through his head. In this way he alighted on the thought of death, and beyond it, of nothing. For an instant he felt like he was dying. ‘It’s obviously a case of an irreversible deterioration of the brain cells,’ he thought on the subject of his unexpected amnesia, something that had never occurred to him before then. He began to sweat and felt an emptiness in his stomach. So, he thought, the pencil was poised over his name; soon he was to be scored off the list of the living and would end up, limbs rigid, on the marble slab of some dissecting room.

Without thinking, he made an appointment at an analysis clinic for the next day, and at seven in the morning he went to have blood and urine samples taken. ‘It’s not as if I’m waiting to be sentenced,’ he thought as he came out of the clinic. ‘The judgement was pronounced long ago, the moment I was cast among the living. It won’t matter if one day I can no longer pronounce the word “I”, because the “I” will no longer exist, or it will be unable to speak. I won’t care.’

He went straight away to see the patients waiting for him. During his visits he noticed with triumphant bitterness that the number of words disappearing from his vocabulary for seconds, for hours at a time was increasing; it was becoming ridiculous. And no longer was it just words with complicated sounds, like plantigrade or clepsydra; even everyday terms, like toothpaste or sand, were beginning to obstruct momentarily the flow of thought in his brain. ‘I’m worse and deteriorating by the minute,’ thought Fleischmann. ‘But it will pass. I’ll get used to it.’

He went to his wife’s house and spent a long time talking with her about trivial things. He was astonished at how sharp and alert he felt. It was as if he had only begun to live from the moment his life had been put in danger. Before, he’d always seemed to be living in a memory, as if in a larval state, a blind thing, completely bereft of consciousness. Now, even his astonishment struck him as an emotion he had never experienced before.

Two days passed in this way. On the third day he went to get the results of his tests. There was a significant alteration in his blood analysis. Three or four values were quite a bit above their normal limits and, left alone, would soon have caused Doctor Fleischmann to have what his colleagues called a Turn. In fact, as he was giving him the written results of the tests Flebus asked him, ‘Have you had a Turn yet? Do you stammer now and again? Get a bit tongue-tied? Have difficulty getting the words out?’ Fleischmann denied that he had. He went home, shut himself in his study and cried.

That evening, with his elbows resting on a clean tablecloth, he looked long and hard at his son, his mother, his wife, all of whom had remained living together after he had moved out. ‘Does any of this make sense?’ He was coming to realize with horror that everything he cared most about – love, affection, responsibility for the lives of his dear ones – was deserting him, leaving him in mocking conversation with a world that was a stranger.

‘You look pale, Papa,’ said his son Benjamin. ‘You’re taking on too many patients. Perhaps if you wrote fewer prescriptions for purgatives and tried to enjoy life a bit more . . .’ Fleischmann knocked over his bowl of soup and stormed out. As he went he saw a terrified, hunted look on the faces of his wife and son.