Psychiatrist Treffert pulls together in this engrossing book his 26 years of research on the mind-boggling phenomenon of the idiot savant. Identical twins George and Charles cannot add or subtract, but they can supply the day of the week for any date from 20,000 B.C. to A.D. 20,000. Leslie--although blind, stricken by cerebral palsy, and possessing an I.Q. of only 58--can repeat without error after a single hearing a 45-minute opera sung in a foreign tongue. Such inexplicable skills combined with gross mental retardation (Treffert calls it ""islands of intelligence"" in a ""sea of severe handicap"") characterize Savant Syndrome. Why are 85% of savants male? Why do most lose their brilliant abilities before adulthood? What explains the savant's ability to perform prodigious mathematical, calendrical, or mnemonic calculations? While Treffert doesn't resolve all these conundrums, he offers some possible solutions, suggesting that savantism makes use of a special memory ""based on unique circuitry"" in the brain, perhaps as compensation for prenatal malformation. Neither pop survey nor technical study, this richly entertaining book deftly weaves together medical and scientific findings (on the nature of memory, PET scans, brain implants, etc.), historical anecdotes, and profiles of three savants with whom the author has worked intensively. Treffert concludes by arguing convincingly--and enticingly--that through studying Savant Syndrome, we may discover ""methods of tapping some of the buried capability"" that he believes lies in every human being. Superior science writing--lucid, exciting, tinged with mystery.