Pickering, a British psychiatrist, demonstrates that while creativity and mental illness have no necessary connection as a rule, the exceptions are always utterly fascinating. He argues convincingly that in the cases of Darwin and Nightingale -- both invalids at an early age -- a diagnosis of ""psychoneurosis"" (specifically Da Costa's syndrome -- palpitation and pain in the heart area) is much more likely than other possibilities; a life as a recluse enabled each to pursue his passion without the drain of normal social intercourse (Pickering differs with Eisely and Moorehead on Darwin). The achievements of Eddy and Freud can be viewed as elaborate endeavors at self-cure of psychoneurosis (Eddy's hysteria and Freud's faintings); and Proust's A la recherche du Temps Perdu is likewise a response to an illness, centering around his mother. Picketing includes Elizabeth Barrett Browning to undercut any generalizations we might make -- ""her invalidism was a pattern of life left over from a previous ongoing illness,"" (probably pulmonary tuberculosis) and her poetry was independent of her disease. The author concludes that apart from the oft-cited prerequisites (intelligence, imagination, discrimination, etc.) creativity comprises some sort of consuming passion, not necessarily ""sick"" or ""normal"" -- a modest but agreeable wind-up to an interesting, if not profound, book.