The need for a framework before seeing diseases
- The evidence was always there, but it made no sense

Oliver Sacks, a neurosurgeon and author, wrote an essay called "Scotoma: Forgetting and Neglect in Science" He describes discoveries that we now know were on track, but which got forgotten or replaced by other theories. He writes "I vividly remember, as a boy, reading a history of chemistry by F.P. Armitage, a former master at my school, and learning that oxygen had been all but discovered in the 1670s by John Mayow. But Mayow’s work was then forgotten and concealed from view by a century of obscurantism (and the preposterous phlogiston theory), and oxygen was only rediscovered a hundred years later, by Lavoisier."

Sacks himself ran into a phenomenom that had been ignored for a hundred years. As a young neurologist in a headache clinic, he would have migraine patients tell him about complex geometric patterns that appeared in their field of vision. When he searched the current literature, he could find no mention of these. He then decided to look at nineteenth century accounts which he said tend to be much richer in description than modern ones. He hit paydirt with a book on migraine written by a Victorian physician in the 1860’s and a paper by John Herschel it referred to written a few years before. "How", asks Sacks, "had these phenomena - startling, highly characteristic, unmistakable hallucinatory patterns - evaded notice for so long?" His explanation is that until recently, there was no way to make sense of them. Now we know, that when there are a large number of elements in interaction, as in the nervous system, "universal behaviors" emerge, which represent the ways dynamic, nonlinear systems organize themselves. They produce the very sort of networks, whorls, spirals and webs that one sees in the geometrical hallucinations of migraine.

Oliver Sacks asks some more questions. At the same time that Herschel reported his spectres, G.B.A. Duchenne, in France, described a case of muscular dystrophy. "As soon as Duchenne’s observations were published, physicians started "seeing" the dystrophy everywhere.. The disorder had always existed, ubiquitous and unmistakable. Why did we need Duchenne to open our eyes?"

Other syndromes, like Tourette’s syndrome, had been described and then neglected for sixty years or more. When a partial cure came along, along with an explanation, the syndrome "seemed to multiply its incidence a thousand fold".

Dr. Sacks ran into the case of a patient who became colorblind after brain damage. He found that the condition had been described in 1888. But then there were no more reports, for seventy five years until Sacks and his colleague Dr. Robert Wasserman studied it. Two other colleagues of Sacks, Semir Zeki and Antonio Damasio, discussed the story. Zeki pointed out that that a belief that we are given our visual images as a whole made this kind of colorblindness seem to be self-evident nonsense, since it implied a separate center for color sensation in the brain. Dr. Sacks points out that theory "can be a great enemy of honest observation and thought", though he also quotes Darwin who said that no man could be a good observer unless he was an active thorizer.

What conclusions does Dr. Sacks come to based on these and other examples that he gives? "It is not enough to apprehend something, to "get" something, in a flash. The mind must be able to accomodate it, to retain it... holding them (new ideas) in mind even if they do not fit, or contradict, one’s existing concepts."