Only a son could have written the life of his parents and, retrospectively, ended his narrative with their marriage; only a trained historian like Flexner could have made such telling use of the rich documentary materials to hand. The story is both one-of-a-kind and, as the title declares, intrinsically American. Simon Flexner (1863-1946), founding director of the Rockefeller Institute for Medical Research, was the laggard, sixth-grade dropout son of a striving, failed Jewish merchant in Louisville-who vainly hauled him off to jail, at ten, to show him his future. (""I had a swell rime."") Helen Thomas (1871-1955) came from Baltimore Quakers of ancient lineage, variable wealth, and vast assurance--dominated by women: Aunt Henrietta Smith, a feminist/evangelist (and the mother of Logan Pearsall Smith, Alys Russell, wife of Bertrand, and Mary Berenson, wife of Bernard); mother Mary, a preacher and feminist of a more mystical bent-presumptively prevented from attaining greatness by the size of her family; and oldest aster M. Carey Thomas, the formidable future president of Bryn Mawr. Both Simon and Helen grew up shy and withdrawn--but she, though greatly advantaged, carried by far the greater burden of guilt: was she hot one of those younger, excess children who had held her mother back? (Did her mother not unwittingly confirm this on her deathbed?) Simon first found himself in recovering from typhoid fever at 16 (""a new beginning""); then, in the drug store of ""the first gentlemen I had ever worked for""; conclusively, at a microscope. His apprenticeship called for him to go to the Louisville College of Pharmacy--where he created his own herbarium, the first serious, independent effort of his life, and, marvel of marvels, won the gold medal that had eluded his older, cynosure brother. The drug store microscope led Simon from specimens to phenomena they embodied; he read about Pasteur and the newly-found principles of biology; and, on the spot, he built ""his own personal, naive, miniature prophecy"" of the Johns Hopkins Medical School, where he would be a student and teacher. How Simon became a local luminary and, with his first dress suit, declared his independence; how he got a medical degree (on the assurance that he'd never practice), so he could go to Hopkins; how he made his mark there--in classroom-teaching, at an Appalachian mine-field; how he became the great Welch's protÃ‰gÃ‰, the colleague of Osier and Halstead. All this is the Ugly Duckling giving birth to modern American medical science (with occasional cuts to brother Abraham, advancing in his own lines). As for Helen, she has her first romantic stirrings--with fierce Bertie Russell and languid Logan Pearsall Smith; trier and fails to write (in emulation of Logan's Trivia, to the disgust of Bertie); suffers a long, debilitating illness; experiences a devoted, difficult friendship; displays not only fortitude but humor, intelligence, charm. Simon and Helen don't actually come together until page 300 or so: ""He said that he had heard of the beauties of the Bryn Mawr campus. . . . Helen offered to give him tea. He answered laughingly that he preferred beer. To this Helen answered that it might not be ladylike to serve beer, but beer he should have."" There is nobility here, and psychological penetration, and ranch gentle amusement.