Forgetting

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There is a goddess of Memory, Mnemosyne; but none of Forgetting. Yet there should be, as they are twin sisters, twin powers, and walk on either side of us, disputing for sovereignty over us and who we are, all the way until death.

For example, right now I am a sixty-nine-year-old biographer, and writing this at a tin table under an olive tree, on the banks of a tiny streamlet known as La Troubadore. In April La Troubadore gushes over a bed of shimmering white shingle, through the young vine fields, until it vaults into the River Droude, a minor tributary of the Gardon.

Actually the Gardon is several rivers – Les Gardons – though no one can agree on quite how many. But they all flow out of the wild hills of the Hautes Cévennes, the two main branches emerging at Anduze and Alès (famed for its municipal fountains). Both are much subject to spring and autumnal flooding (la crue), and regularly carry off the cars and houses of the plain. They join forces further south, near Avignon, and as one mighty waterway sweep under the Pont du Gard, the noble Roman bridge built by the Emperor Augustus, with its fifty-three striding stone arches, one row balancing airily upon another, like some brilliant troupe of performing circus elephants, those creatures that never forget.

Paradoxically, this famous Roman bridge is really an aqueduct, and the river beneath it never becomes the Gard. Indeed, there is no River Gard at all, except possibly, momentarily, at the point where it goes under the Pont du Gard. I have heard a local fisherman quote Heraclitus on this subtle question. Certainly, when it comes out the other side, the river is still Le Gardon, and flows on down to join the stately Rhône near Arles and Tarascon, and so out into the Mediterranean, untroubled by its many identities.

Yet they change constantly. By August my sparkling young Troubadore is quite dry and silent. Its shingle is hot and dusty, like a line of white bones laid along a ditch. The cheerful Droude has dwindled to a fretful ghost, green and malodorous, skulking under the trees. Even the two muscular Gardons have fallen into a brown study, a long slack chain of slumbering rock pools, barely threaded together by a trickle of live water, marooning thousands of tiny distracted fish. So, it seems, are the seasons of Memory and Forgetting, forever alternating between flood and drought.

Here at my tin table, with the cicadas beating their jazzy Django Reinhardt sound, I am flooded with memories of the Cévennes of fifty summers ago. I arrived on the night train from Paris, with its dark creaking woodwork and circular windows, and the pink dawn coming up over Pont-Saint-Esprit and Orange. Getting out at Avignon, I was told that all the autocars were ‘en Grève’. I studied my map for some time to find this desirable place, Grève. Later it was explained to me that Grève was not a location, but a condition. To be en grève meant to be ‘on strike’. It now occurs to me that to be en grève could also be a state of mind.

So I hitch-hiked instead to Uzès, getting a lift in the van from the Cave Co-operative. We drove past the cimitière, to the Mas Saint-Quentin, where Monsieur Hugues was ploughing between his vine rows with his grey horse called Mistral. He completed his row and came over to the side of the field, pushing his cap onto the back of his head, and shook my hand with a certain caution. ‘Un jeune Anglais, pardée!’ I stayed with his family in the mas for the next five months, and, in a series of long walks westwards, discovered the Cévennes.

But just here memory falters, and runs dry. I see Monsieur Hugues so clearly at that moment at the field’s edge: the walnut-brown face, the outstretched arm, the shy glance from under the cap, the big old leather belt with the army buckle, and the red-check handkerchief pulled out to wipe his face. But red-check – was it? Or did that belong to the other farmer who, weeks later, I met in a high alpine field near Mont Lozère in the Cévennes, under a burning midday sun? The farmer who stopped his hay-making to give me an ice-cold swig of water from his canteen, tucked under the tractor seat, and wrapped in a damp cloth to keep it cool. A red-check cloth perhaps? Was it his?

Or was it even the neckerchief that belongs to Monsieur Rolland, the farmer who lives across the track from us now, an eighty-year-old who adores his vines, his dog and his grandchildren, and shakes my hand across the stone wall, bringing us grapes? Whose red-check handkerchief, whose walnut-brown face, whose eternal shy kindness of the Midi, am I actually remembering? And was that horse that I used to groom in the evenings in the courtyard of the Mas Saint-Quentin, to the smell of roasting chicken and rosemary, really called Mistral?

So here is Memory mixed with Forgetting, and maybe combined with what the neuroscientists call ‘confabulation’, or unconsciously making it up. Two sparrows dive down and brawl in the dust under the apricot tree. Little bursts of hot wind from the south scrape the big, heart-shaped leaves of the murier d’Espagne across the terrace. I listen to this drowsy orchestration of the leaves, the cicadas, the fountain, the tractor, the mid-afternoon bell from the village striking the Angelus. I fall asleep for a few moments while making these notes. I dream, something about rivers and flooding. But when I wake I cannot remember what it was. I find myself wondering if the rivers used to dry up like this fifty years ago, when I was young.

Later I discovered the answer in my battered copy of Napoléon Peyrat’s Pasteurs du Désert (1842). This was Robert Louis Stevenson’s favourite book about the Cévennes, which forms the haunting background to his Travels with a Donkey. Peyrat vividly recounts the history of the Camisard rebellion of 1702–05, and the memoirs of the visionary young soldier-prophets who came down from the hills to fight against their royalist oppressors on the plain. It was a Protestant insurrection against Catholic authority, but also a mountain people’s insurrection against the centralised power of the city and the plain.

In the opening chapter of Volume Two there is a passage describing the dashing Camisard leader Jean Cavalier. It recounts his successful ambush of the King’s dragoons at the Pont de Ners, just five kilometres from my olive tree, where the Droude meets the Gardon below Anduze. Peyrat also makes a remarkable observation about the fluctuating state of the rivers, and what it might symbolise:

In springtime during la crue, the Gardon often bursts its banks and sweeps like an inland sea towards the village of Boucarain. But in the growing heat of summer, all this mighty torrent shrinks back again to expose a huge dry plain of sand and pebbles. Its panting ardour expires upon the banks of shingle [grève, once again], until it is little more than a tiny pulse of water which the burning sun of the Midi soon dries up completely. So the Gardon is symbolic of the Cevenol revolt, as excessive in its triumphs as in its defeats. Moreover, the river would never countenance a bridge to be maintained at Ners. It would ruthlessly wash away each successive set of arches, as soon as they were built. Beside their eternally ruined stonework, a simple ferry boat, plying between one bank and the other, remained the most reliable method for travellers.

So the Gardon had always fluctuated violently; and sometimes even become the River Lethe too.

Here is something one of my students at the University of East Anglia, Marisse Clarke, told me about forgotten memories. Marisse was completing her MA in Life-Writing, and working on a project to reconstruct the domestic history of pre-war Norfolk. It was a jump-back of sixty years or more to ‘the pre-fridge era’, as she called it. There was lots of written material, especially letters and diaries, in the Norwich archives, but she was interested in something more direct and intimate, an oral history. Her main source became groups of old-age pensioners, many of them women, who met once a week for ‘reminiscence sessions’. Initially they were shy, their memories were very scattered, and it was difficult to get more than a few well-worn tales. On subjects such as ‘Christmas’, Marisse suspected many memories were made up of ‘fanciful images’, unconsciously adapted from popular Christmas tales, films or Christmas cards (confabulation again).

Then a colleague told her about the ‘memory boxes’ that had been taken along to other reminiscence sessions. A memory box typically consisted of a large suitcase containing a number of perfectly humdrum domestic objects from the 1930s – a bar of Lux soap, a box of Swan Vesta matches, an Ovaltine tin, a tortoise-shell hairclip, a small mangle, and so on. For a ‘Wash Day and Bath Night’ session, things like stone hot-water bottles and men’s traditional cut-throat razors were added – and the memory box itself became an old zinc bath.

According to Marisse, what many of us would regard as ‘old junk’ now became ‘little treasures’ of stored-up memory, with a high symbolic value. The effect of the memory boxes was often magical. The old women, many in their eighties, slowly began to handle, identify (eyesight not always so good) and discuss these familiar objects. Amazement was soon followed by laughter, delight, and not infrequently indignation, and even some tears. Each physical object would ‘trigger’ a long chain of recollections. Gradually an extraordinary stream of shared memories, anecdotes, jokes and stories would emerge. The flow – the flood – soon became unstoppable. It was quite unlike anything Marisse or her colleagues had heard before, and the memories had a knock-on or chain-reaction effect, each memory setting off another. Sometimes, it seemed, the evenings would explode into a party, a memory party.

This was the starting point for a brilliant MA dissertation on oral history, old age and community memory: Wash Day and Bath Night: Uncovering Women’s Reminiscences (2003). What did it demonstrate? Certainly that Marisse was a very good researcher, and knew how to wait, how to listen, and how to gain trust, like all good potential biographers. But also that memory and forgetting are subject to the law of association.

The concept of the association of ideas is at least as old as Aristotle in the fourth century BC. The argument was taken up by Hobbes and Pascal, and later elaborated by David Hume in his Treatise on Human Nature (1738). Hume suggested that ideas were naturally linked by three qualities: ‘resemblance, contiguity in time or place, and cause and effect’. But it took an eighteenth-century doctor to transform these metaphysics into a scientific theory of memory.

One of the great, forgotten books of English Romanticism is David Hartley’s Observations on Man, His Frame, His Duty and His Expectations, first published in 1749. Hartley was a successful physician who turned his hand to philosophy and psychology. Born in Yorkshire, he practised largely in London and Bath, where he developed a theory of consciousness based on his own medical observations of his patients. Hartley’s great originality was to consider memory primarily as a physiological process. It was something that occurred not only in the ‘mind’, but physically in the structure of the brain. Combining the empirical philosophy of Locke with his own views of the human nervous system, he argued that all memories were formed by ‘clusters’ or sequences of associated impressions and ideas. These were physiologically encoded in the brain in an enormous network of medullary ‘vibrations’, or smaller ‘vibratiuncles’, similar to electrical impulses moving through the brain tissue or ‘medullary substance’.

Although Hartley had not carried out dissections of the cerebral cortex, and had no effective map of the human brain (as we do today), his theories strikingly anticipate much speculative modern neuroscience. For example, Francis Crick’s study The Astonishing Hypothesis (1994), with its characteristically provocative subtitle The Scientific Search for the Soul, proposes ‘40-Herz oscillations’ within the brain, and ‘reverberations’ within the cortex, as the possible basis of human consciousness: ‘Consciousness depends crucially on thalmic connections within the cortex. It exists only if certain cortical areas have reverberatory circuits … that project strongly enough to produce significant reverberations.’

In their most basic form Hartley’s associative clusters were linked to simple impressions of pleasure or pain, but they eventually organised themselves hierarchically. They evolved into all the higher forms of remembered knowledge, learning and reason. They evolved into notions of imagination, ambition, conscience and love. They even evolved into a belief in God, which Hartley called ‘theopathy’.

Hartley was a philanthropist, a vegetarian, a Christian and a believer in a mystical kind of Paradise. Yet in effect he was putting forward a theory of the entirely physical or ‘material’ evolution of the human brain. He saw no sign of the traditional division between mind and body. He detected no separate interjection of a ‘spirit’, a ‘divine spark’ or a soul. Memory was a form of electrical or chemical motion. As he put it in his famous Proposition 90: ‘All our voluntary powers are of the nature of Memory.’

Hartley also had an unusual theory of dreams. Far from being coded messages from the unconscious, they were simply part of the brain’s system of waste disposal. When we dream, we abandon the useless memories and associations of the day. Dreaming is a functional form of forgetting, which prevents the machinery of the brain from becoming overloaded. Without forgetfulness, we would become mad: ‘The wildness of our dreams seems to be of singular use to us, by interrupting and breaking the course of our associations. For if we were always awake, some accidental associations would be so cemented by continuance, as that nothing could afterwards disjoin them; which would be madness.’

These ideas strongly attracted the eighteenth-century scientist and free-thinker Joseph Priestley. Priestley was fascinated by various forms of chemical and electrical energy, and suspected that the human brain contained both. (He had a taste for daring innovations, and was the first to isolate, though not to identify, oxygen gas consumed in combustion.) In 1774 he edited a new edition of Hartley’s Observations with his own Preface. ‘Such a theory of the human mind … contains a new and most extensive science,’ he wrote. ‘It will be like entering upon a new world, affording inexhaustible matter for curious and useful speculation.’

But others were profoundly shocked. Thomas Reid, a Professor of Moral Philosophy from Edinburgh, observed that ‘the tendency of Hartley’s system is to make all the operations of the mind mere mechanism, dependent on the laws of matter and motion’. The horrific idea of human memory as a ‘mere mechanism’ inspired Reid to unleash a superb passage of polemic science fiction in his Essays on the Intellectual Powers of Man (1785): ‘If one should tell of a telescope so exactly made as to have the power of feeling; of a whispering gallery that had the power of hearing; of a cabinet so nicely framed as to have the power of memory; or of a machine so delicate as to feel pain when it was touched; such absurdities are so shocking to common sense that they would not find belief even among savages …’

It does not weaken Reid’s metaphysical outrage to observe that three hundred years later, most of these ‘absurd’ and incredible machines do exist. Certainly one could argue that the laparoscope (introducing carbon-fibre optics within the body), the mobile phone, the desktop computer and the MRI scanner demonstrate respectively many of the impossible features Reid describes.

More surprisingly, Hartley’s Observations deeply impressed a Romantic poet. In his extraordinary effusion of 1796 entitled ‘Religious Musings’ (a sort of intellectual tour d’horizon written at the age of twenty-three), Coleridge grouped David Hartley with Newton and Priestley as one of the three visionary English scientists who had truly glimpsed a ‘renovated Earth’. He described Hartley as the ‘wisest’ among scientific thinkers, who had fearlessly explored the human mind, and become (in a prophetic image)

… The first who marked the ideal tribes

Up the fine fibres through the sentient brain.

Many of Coleridge’s most subtle early poems, such as ‘Frost at Midnight’ (1798), with its complex patterns of memory association, are explorations of Hartley’s theories. Like a memory box, this poem contains a series of physical objects and sensations – an owl’s cry, a flickering fire, a baby’s cradle, the sound of church bells – which reverberate into an ever-expanding orchestration of memories. These also produce, like complex harmonies, several layers of past and future identity. The adult Coleridge becomes a child again; while the child remembers he has become a father; and the father blesses the child. It is no coincidence that the actual baby in this poem is Coleridge’s eldest son, Hartley, born near Bristol in 1796 and named in honour of the philosopher-doctor.

Coleridge’s later Notebooks have many passages exploring the phenomenon of memory association, such as those connected with his beloved ‘Asra’, Sara Hutchinson. In an agonised notebook entry for 5 March 1810, when she was preparing to leave him, he wrote down an enormous catalogue of all the objects which by ‘the Law of Association’ reminded him of her – from a piece of music to a waterfall, from a bedroom door ajar to the delicious white sauce on a joint of meat. He described them as forming a powerful cluster of ideas, almost unbearably strong and vivid, ‘that subtle Vulcanian Spider-web Net of Steel – strong as Steel yet subtle as the Ether – in which my soul flutters enclosed with the Idea of your’s’.

Here Hartley’s ‘vibrations’ have been subtly transformed back into a ‘flutter’ of the soul; a word that also occurs at a key place in ‘Frost at Midnight’. In this beautiful and observant passage, Coleridge uses the faint flicker of convected air above his fire (the mirage-like ‘film’, not the visible flame) to produce a remarkable image of human consciousness itself. It is essentially unstable, dynamic and playfully inventive.

… the thin blue flame

Lies on my low-burnt fire, and quivers not;

Only that film, which fluttered on the grate,

Still flutters there, the sole unquiet thing.

Methinks, its motion in this hush of nature

Gives it dim sympathies with me who live,

Making it a companionable form,

Whose puny flaps and freaks the idling Spirit

By its own moods interprets, every where

Echo or mirror seeking of itself,

And makes a toy of Thought.

Coleridge would go on to dedicate three entire chapters of his Biographia Literaria (1817) to the history of Associationism ‘traced from Aristotle to Hartley’. In one place in Chapter 6, he remarked that Hartley’s theory of memory could be compared to ‘a broad stream, winding through a mountainous country with an indefinite number of currents, varying and running into each other according as the gusts chance to blow from the opening of the mountains’.

In one form or another, the theory of Associationism remained hugely influential throughout the Romantic period. The radical idea of memory as a physiological process was seen to provide a possible link between human consciousness and the rest of the living world, however remote. Coleridge had written of ‘dim sympathies’ with ‘companionable forms’. More than seventy years after Hartley’s Observations, the great chemist Sir Humphry Davy was exploring Associationism in connection with freshwater fish in his book Salmonia, or Days of Fly-Fishing, published in 1828.

He was investigating the mysterious memories of fish, which he regarded as quite as interesting a phenomenon as those of human beings. For example, once a trout was caught and thrown back into the river, could it remember being hooked? Could it remember the pain of being hooked? Could it feel – or remember – pain at all? And if so, was trout-fishing inherently cruel? This seems an astonishingly modern question: ‘But do you think nothing of the torture of the hook, and the fear of capture, and the misery of struggling against the powerful rod?’

Davy debates these issues in a series of dialogues, which gain an added poignancy from the fact that he himself was ill, in pain and near death at the time he wrote them. ‘My only chance of recovery is in entire repose,’ he wrote from the shores of Lake Constance in July 1827, ‘and I have even given up angling, and amuse myself by dreaming and writing a very little, and studying the natural history of fishes … I now use green spectacles, and have given up my glass of wine per day.’

He concludes that although a trout may not feel pain in a human sense, it does remember being hooked, and afterwards may subsequently ‘refuse an artificial fly day after day, for weeks together’. Davy thought the reason for this was that the trout associated the pain with the place: ‘The memory seems local and associated with surrounding objects; and if a pricked trout is chased into another pool, he will, I believe, soon again take the artificial fly. Or if the objects around him are changed, as in Autumn, by the decay of weeds, or by their being cut, the same thing happens.’

One afternoon about five years ago I was walking around a favourite flowerbed in Norfolk, which my beloved Rose and I had dug and planted from scratch. Every plant and shrub was an old friend – iceberg roses, Hidcote lavenders, blue hydrangeas, magnolia, purple berberis, red-tipped photinia, Japanese anemones, scarlet crocosmia, white potentilla. Then I came to a pleasant, green-tufted shrub which had once been the size of a modest pincushion and was now more like that of a plump chaise-longue. I had often fed it, clipped it, hoed uxoriously under its skirts. I had, frankly, often wished to sprawl full length on its springy, inviting mattress of minute green foliage and tiny white flowerets.

But on this particular afternoon I gazed down at its familiar, cheery, hospitable shape and realised that I had totally forgotten its name. For several uncomfortable minutes I stared blankly at it, reaching into the pocket of my memory and finding it alarmingly empty, just as if I had suddenly lost a set of car keys. Only when I turned to walk back up the lawn, and was momentarily distracted by the flight of a pigeon above the beech trees, did the name ‘hebe’ spring effortlessly to mind.

Of course this is a common phenomenon among the late-middle-aged. (Is it called ‘nominative aphasia’? I can’t remember.) It applies particularly to the names of specific things – people, places, books, or – as in my case – plants. It can be combated, especially by child-like mnemonic devices. ‘Hebe-jeeby’ has rarely failed me since. Nevertheless, it tends to spread steadily and insidiously once it has begun. No one has quite explained its causes. I know a computer expert who calls it the ‘disk full’ effect; while others speak of ‘senior moments’, or hardening cerebral arteries, weakened synaptic links, alcohol, tea-drinking, metaphysical distraction, existential anxiety, incipient dementia, or just the middle-aged mind generally ‘on other things’ – though not necessarily higher ones.

This kind of forgetting certainly belongs to the goddess who has no name. Yet it is not so much a failure to remember – more a failure to recollect. The missing word, the absent object, has not really disappeared; rather, it has become temporarily and mysteriously unavailable. Moreover, the act of recollection works in a curious way. When I actively tried to recollect, it was as if I was constantly on the brink of remembrance, or stuttering with a word, or slipping back from the last few inches of a rope-climb. But the moment I stopped trying, the moment I looked up and admired the pigeon in his evening swoop over the beech trees, the word ‘hebe’ arrived without effort, without strain, like a free gift.

Coleridge was one of the first to describe this phenomenon of ‘active and passive recollection’, in his Biographia. It also appears in the remarkable Chapter 6, where he compares the mental law of Association with that of the physical law of gravitation: ‘it is to Thought the same, as the law of gravitation is to locomotion’. Sometimes we actively strive for memory, sometimes we passively yield to forgetfulness. When someone is ‘trying to recollect a name’, he uses ‘alternate pulses of active and passive motion’. The surprising analogy Coleridge gives for this mental process is that of a tiny water-beetle paddling its way up the surface of a stream. He adds that a very similar active-passive is at work in the composing of poetry. The passage, with its impression of Coleridge himself bending over the surface of the water (or the mind), minutely observant, half poet and half scientist, is itself a kind of mnemonic image:

Now let a man watch his mind while he is composing; or, to take a still more common case, while he is trying to recollect a name … Most of my readers will have observed a small water-insect on the surface of rivulets, which throws a cinque-spotted shadow fringed with prismatic colours on the sunny bottom of the brook; and will have noticed how the little animal wins its way up against the stream, by alternate pulses of active and passive motion, now resisting the current and now yielding to it in order to gather further strength and a momentary fulcrum for a further propulsion. This is no unapt emblem of the mind’s self-experience in the act of thinking. There are evidently two powers at work …

The power of what has been forgotten can sometimes be as great as that which has been remembered. In Edward Thomas’s poem ‘Old Man’, the unnamed bush that stands outside his cottage door has a tiny leaf with a dark, bitter, haunting smell. It evokes something he can never quite place or explain. Each time he rubs it between his fingers, the scent sweeps him back to the borders of a primitive memory, which is never quite rediscovered:

As for myself

Where first I met the bitter scent is lost.

I, too, often shrivel the grey shards,

Sniff them and think and sniff again and try

Once more to think what it is I am remembering,

Always in vain. I cannot like the scent,

Yet I would rather give up others more sweet,

With no meaning than this bitter one.

I have mislaid the key. I sniff the spray

And think of nothing; I see and hear nothing;

Yet seem, too, to be listening, lying in wait

For what I should, yet never can, remember …

Only an avenue, dark, nameless, without end.

Thomas’s poem also reminds one of the peculiar power of smell to summon up – to call back – specific memories (especially of places). I have an aftershave which instantly recalls a certain room in a motel in Pacific Grove, near Monterey, in California.

Marcel Proust observed in À la Recherche du Temps Perdu that the smell and taste of things are ‘more faithful’ than visual images. They remain suspended in the mind for a long time, ‘like souls ready to remind us, waiting and hoping for their moment to come amid the ruins of all the rest; they bear unfaltering, in the tiny and almost impalpable drop of their essence, the vast structure of recollection’.

That was written in 1913, as Proust reflected in Paris on the extraordinary power of the madeleine dipped in the tisane to call back the memories of his country childhood in Combray. It has become the classic literary reference to the power of smell and taste to summon memories. But five years earlier, in a dark lane near the River Thames, another equally powerful summons – with the force of ‘an electric shock’ – had already been recorded:

We others, who have long lost the more subtle of the physical senses, have not even proper terms to express an animal’s intercommunication with his surroundings, living or otherwise, and have only the word ‘smell’ for instance, to include the whole range of delicate thrills which murmur in the nose of the animal at night and day, summoning, warning, inciting, repelling. It was one of those mysterious fairy calls from out of the void that suddenly reached Mole in the darkness, making him tingle through and through with its very familiar appeal, while as yet he could not clearly remember what it was. He stopped dead in his tracks, his nose searching hither and thither in its efforts to recover the fine filament, the telegraphic current, that had so strongly moved him.

This of course is the Mole from Kenneth Grahame’s The Wind in the Willows (1908), trudging along one freezing December night on his way back to Ratty’s snug riverside burrow, when suddenly ambushed by olfactory memory. He too does not know for some moments what he is smelling, only that its associations are bewilderingly strong. Then finally comes ‘recollection in the fullest flood’. What he is smelling is ‘Home!’ and his own past life there (back in the spring). ‘Now, with a rush of old memories, how clearly it stood up before him in the darkness!’

Smell can be piercingly direct in its transporting power. In his autobiography, Something of Myself (1937), Rudyard Kipling describes a very particular, pungent kind of woodsmoke, made up of burning tar, old ammunition boxes and railway-sleepers, with which he says he could move an entire battalion of men (and a lion cub) to the veldt of South Africa, by reactivating their memories of the Boer War. Yet the precise action of smell on the human memory still remains mysterious.

In October 2004 the Nobel Prize for Physiology was presented to two American scientists, Richard Axel and Linda Buck, for a brilliant paper on the connection between the nose and the brain. They established that the human nose has nearly a thousand separate ‘receptors’ (ten times more than a fish, though forty times less than a dog). These have complex connections with the cortex, involving no less than 3 per cent of our genes. They form unique clusters, or ‘olfactory patterns’, which are capable of holding ‘memories of approximately 10,000 different odours’, a truly astonishing resource. Yet when asked, in the course of an interview for the BBC World Service, what light their prize-winning work threw on Proust’s experience, Richard Axel answered simply, ‘None at all.’

In her popular science book The Human Brain: A Guided Tour (1997), Susan Greenfield concludes, in a way that David Hartley would surely have recognised, that ‘Memory is a cornerstone of the mind.’ But, writing as a Professor of Pharmacology, she still emphasises how little can be said definitely about the relationship between its ‘phenomenological and physical’ functioning. There is no generally accepted theory of how the brain produces the mind, or the mind generates consciousness, or of how consciousness depends on memory. The human brain has one hundred billion cells, and their infinitely complex interaction remains much more mysterious than the functioning of an entire galactic star system. Perhaps there is something oddly reassuring about this.

Neurological experiments have proved that there is a short-term memory (which seems to be connected to the hippocampus, and lasts up to thirty minutes). There is also a separate long-term memory, which may last over ninety years, and seems to be distributed throughout the cerebral cortex. Amazing feats of memory have also been accurately studied and measured in the performance of chess-players, musicians, actors, sports aficionados (entire Wisdens committed to memory) or autistic patients. One vividly recalls the sweating Memory Man’s public performance in the dramatic finale to Alfred Hitchcock’s film The Thirty-Nine Steps (1935); though it is easy to forget that he does not in fact appear in the original novel (1915) by John Buchan.

Nevertheless, the actual way in which a single, discrete memory (if there is such a thing) is ‘recorded’ in the human brain remains bafflingly obscure. Writing of Wilder Penfield’s open-brain surgical experiments in Canada in the 1950s, Greenfield observes, ‘The clinical cases reported by Penfield would also suggest that memory is not stored simply: it is not laid down directly in the brain. Rather, as seen in Penfield’s studies, a cache of memories would be more like a nebulous series of dreams. One immediate problem was that the memories themselves were not like highly specific recordings on a video and were a far cry from the memories on a computer. Another problem was that if the same area was stimulated by Penfield on different occasions, different memories were elicited. Conversely, the same memories could be generated from stimulating different areas. No one has yet shown definitively how these phenomena can be explained in terms of brain functioning.’

Nevertheless, the basis of all memory still seems to be conceived as the establishment of ‘associations’ through clusters or ‘networks’ of neuronal links: ‘We know that long-term memory is accompanied by an increase in the number of presynaptic terminals, and we know that memory involves establishing new associations.’ Chemical transmitters, voltage changes and synaptic ‘circuits’ have partly replaced Hartley’s speculative ‘vibrations’, although the old imagery of flood and drought is still hauntingly present. Explaining the role of calcium in forming a neuronal connection, Greenfield writes of the glutamate receptor cell ‘opening the channel for calcium ions to flood in’, and subsequently of the ‘large influx of calcium’ strengthening the synapse by releasing ‘a chemical cascade within the target cell’.

Neuroscience also recognises many types of forgetting, though most of these are pathological. They include numerous kinds of brain damage; various forms of post-traumatic amnesia; Korsakoff’s syndrome (based on severe dietary deficiency); alcoholic blackouts and lapses; Wernicke’s aphasia, in which speech itself is unlearned; Parkinson’s (in which the brain forgets physical coordination); and of course Alzheimer’s, which is not a natural consequence of old age, but a very specific degenerative disease of the medial temporal lobe.

Forgetting as a more positive, constructive, or even healing process – both for individuals and for whole societies, such as post-Apartheid South Africa – has begun to receive more attention. And then there is always the ‘benign protective amnesia’ of old age, as reflected in Groucho Marx’s memorable aside: ‘I never forget a face, but in your case I’m prepared to make an exception.’

Old age brings one particularly enigmatic feature of the lifelong exchange between Memory and Forgetting. It is the striking, but apparently paradoxical, fact that as old people begin to forget their immediate past, they often begin to remember their distant childhood with startling vividness. What possible metaphysical or physiological explanation can be given for this phenomenon?

Susan Greenfield calls it, among all the common processes of human memory, ‘the most mysterious issue of all’. Characteristically, she sees the problem in terms of cellular loss and renewal: ‘We know that some people can remember what happened to them ninety years ago, but by then every molecule in their body will have been turned over many times. If long-term changes mediating memories are occurring continuously in the brain, how are they sustained?’ This paradox had already been observed by Leonardo da Vinci, in one of his notebooks known as the Codex Atlanticus, at the beginning of the sixteenth century: ‘Things that happened many years ago often seem close and proximate to the present time, and many things that happened recently seem as ancient as the long-gone days of youth.’

Coleridge saw the problem in psychological terms. He suggested shrewdly that memories of childhood have a high visual content, with strong associated moods, but lack linguistic or spoken elements: ‘If I were asked how it is that very old people remember visually only the events of early childhood, and remember the intervening spaces either not at all or only verbally, I should think it a perfectly philosophical answer that old age remembers childhood by becoming a second childhood!’

Coleridge expanded on this in a letter to his friend Robert Southey in August 1803: ‘I hold that association depends in a much greater degree on the recurrence of resembling states of feeling than in trains of ideas; that the recollection of early childhood in latest old age depends on and is explicable by this.’ He added that if flows of feelings, rather than discrete chains of ideas, formed the essential structure of memory, then Hartley’s system was too atomistic and passive: ‘Hartley’s system totters.’

In fact Coleridge came to consider (like Bergson, like Proust) that perhaps nothing was really ever forgotten. Perhaps movements of feeling, vibrations of emotion, were capable of resurrecting almost anything from our past lives. He wrote in a notebook of 1803: ‘For what is Forgetfulness? Renew the state of affection or bodily Feeling, same or similar – sometimes dimly similar – and instantly the trains of forgotten thought rise up from their living Catacombs!’

Yet in the Preface to his unfinished ‘Kubla Khan’ (1816), Coleridge described the most famous incident of creative forgetting in English literature. Retired to a lonely farmhouse near Exmoor in the autumn of 1797, he took opium and dreamed a poem of ‘not less than from two to three hundred lines’. On awaking he wrote down the first fifty-four lines (as we now know ‘Kubla Khan’), but was interrupted by ‘a person on business from Porlock’. He could never recall the rest of the poem.

The analogy Coleridge uses for this moment of forgetfulness is, once again, water: ‘… On his return to his room, [he] found, to his no small surprise and mortification, that though he still retained some dim recollection of the general purport of the vision, yet, with the exception of some eight or ten scattered lines and images, all the rest had passed away like the images on the surface of a stream into which a stone had been cast, but, alas! without the after restoration of the latter!’

Most modern critics and biographers think that Coleridge invented the person on business from Porlock, to hide the fact that he simply could not finish the poem. But I think he was visited first by Mnemosyne, and then by the other goddess. It was just that he could not remember her name.