The River of Consciousness

Many of you will be aware of the work of the late Dr Oliver Sacks, who sadly died in August, 2015. Among his most celebrated books are "Awakenings" and "The Man Who Mistook his Wife for a Hat". His memoir, "On The Move", was published shortly before his death and the book now reviewed, "The River of Consciousness", was assembled posthumously by his three editors. In their introduction, his editors explain that one of the many catalysts for the book was an invitation Oliver Sacks received in 1991 from a Dutch film-maker to participate in a documentary television series called "A Glorious Accident". In the final episode, six scientists- the physicist Freeman Dyson, the biologist Rupert Sheldrake, the paleontologist Stephen Jay Gould, the historian of science Stephen Toulmin, the philosopher Daniel Dennett and Oliver Sacks -gathered around a table to discuss some of the most important questions: the origin of life, the meaning of evolution and the nature of consciousness.

"The River of Consciousness" honours the extraordinary observational acuity of Sacks' three great heroes- Charles Darwin, Sigmund Freud and William James. Moreover, and crucially, Sacks celebrates the trajectory of widening and deepening Man's often rather patrician view of nature, particularly regarding the sentience and emotional responsiveness of other species.

Sacks' humility is obvious in all his books and he deliberately seeks out this trait in other scientific observers. Thus, he draws our attention to Darwin's thoughtful experiments and theories which questioned Carl Linnaeus' doctrine of self-fertilisation of flowers. Darwin's proposal that flowers' special features - patterns, colours, shapes, nectars and scents - were lures to flying insects to promote pollination became ground-breaking in illuminating the co-evolution of plants and insects. Indeed, whilst Darwin's ideas of plants' tendrils being exquisitely sensitive to gravity, pressure, moisture, sunlight and chemical gradients were roundly dismissed in his day, research some fifty years later was to demonstrate that subtle plant hormones like auxins play many of the roles that nervous systems do in animals.

Sacks draws us further into the immense scope of consciousness within nature by describing Darwin's conviction that the ability of plants and animals to modulate responses indicates "the presence of a mind of some kind" (quoted from Darwin). Sacks recounts in lyrical prose the work of George John Romanes who, in 1885, published a beautifully illustrated book on primitive nervous systems in jelly-fish, star-fish and sea-urchins. Romanes was to speak of his own work as "comparative psychology" and his main enterprise as an attempt to correlate the neural and the behavioural. Only once in the book does Sacks deliver a thundering excoriation in his condemnation of Descartes' vivisection of animals to prove that their cries of pain were only reflexes.

Having introduced us to such pioneers, Sacks leads us into the world of human consciousness. He takes pains to honour the early neuro-anatomical work of Sigmund Freud, who established that it was not the morphology of nerve-cells that differed between primitive and advanced animals, but their organisation. Following work by the eminent neurologist, Paul Broca and others, the human cerebrum was mapped, correlating location with function. Sacks indicates to us that Freud was deeply dissatisfied with what he considered to be an overly mechanical thesis which regarded the brain as an ingenious, but idiotic, machine. Instead, Freud invoked the idea of "cortical fields", large areas of cortex endowed with a variety of functions. Throughout the book, Sacks celebrates the exceedingly rare conjunction in truly great scientists of: meticulous acquaintance with structure; the ability to carefully penetrate experience and observe function; the courage to challenge orthodoxy, often enshrined as dogma; finally, the exceptional talent of positing genuinely novel coherent theories.

Characteristic of his focus on the subjective, Sacks gives us vignettes of his own experience as he ages. His treatise on the fallibilities of memory and his own mis-hearings are typically humble and amusing. His treatment of creativity is wide-ranging and is punctuated with illuminating quotes from inspired creators as diverse as Henri Poincare and the composer Wagner. Speaking of himself, Sacks describes his own epiphanies with these words: "I feel I can bypass or transcend much of my own personality, my neuroses. It is at once not me and the innermost part of me, certainly the best part of me."

In a chapter which shares the book's title, Sacks takes us on a fascinating elucidation of the nature of "the stream of thought", to quote William James. Indeed, James' ideas are cradled along with those of Henri Bergson, James Mill (father of John Stuart Mill) and Sir Charles Sherrington. Seamlessly, he moves forward with the work of Francis Crick and Christof Koch in pioneering the study of the neural basis of consciousness. Sacks pays a final tribute to William James by invoking James' idea that the coherence of consciousness depends upon each thought being born the owner of the thoughts that went before and (in James' words) "dies owned, transmitting whatever it realised as its Self to its own later proprietor". To me, this is a wonderful premonition of the later work of Alfred North Whitehead.

In his last chapter, Sacks highlights the oddly fragmented nature of scientific discovery much, perhaps, like biological evolution itself. Here, with characteristic modesty, he recalls his own observations of his neurological patients and contrasts the powerfully descriptive accounts of nineteenth century observers with the more formulaic and impoverished accounts of the last 120 years. His thesis is that fragmentation of scientific enquiry often follows the pure, descriptive phase and that the evolution of a coherent model requires an understanding of determinants at every level. Symbolically, Sacks uses the condition of scotoma (derived from the Greek for darkness) to parallel the blind-spots we may encounter in scientific enquiry. He is avid in encouraging us to take note of exceptions and to not forget or dismiss them as trivial. He quotes Wolfgang Koehler, a pioneer gestalt psychologist: "Each science has a sort of attic into which things are almost automatically pushed that cannot be used at the moment, that do not quite fit…… We are constantly putting aside, unused, a wealth of valuable material that leads to the blockage of scientific progress."

Sacks goes on to provide several examples of prematurity in science: Gregor Mendel; Oswald Avery who discovered DNA in 1944; Barbara McClintock who proposed jumping genes in the 1940s. This is no new phenomenon – Aristarchus in the third century B.C. clearly established a heliocentric model of the solar system which was swept away by Ptolemy's absurdly complicated geocentric confabulation five centuries later. This latter scotoma was to last a mere 1400 years and was, of course, defended with almost militaristic fervour. Sacks believes that Freud would explain this by emphasising resistance: the new idea is deeply threatening and hence is denied access to our full mind. A fitting homily to us all!

Sacks' emotional intelligence shines through all his published work and one feels sure that those whom he knew personally, including his beloved patients, will remember him as deeply intelligent, insatiably curious and incurably modest. This book is a fitting epitaph to a poet of medicine and science and an encourager to all authentic seekers.