He is a second Dirac,"" Princeton's Eugene Wigner said, ""only this time human."" That's only one of the many pithy descriptions that Gleick (Chaos, 1987) quotes in this fine, monumental biography of a monumental figure in 20th-century physics. Readers whose appetites were whetted by the as-told-to collections of anecdotes in the Ralph Leighton books (Tuva or Bust!, 1991, etc.) will find gratification of a different kind here. There are wit and playfulness, yes, but what shines through is Richard Feynman's commitment to probe nature, a restlessness to understand why things happen, and the joy and beauty he felt when science yielded an answer--and that is the key to understanding what drove Feynman throughout his life. That, and a no-nonsense attitude that despised pretension, lofty language, and rote learning. In the post-Sputnik clays of educational reform, Feynman was out in front criticizing the new math as utterly useless formalism (unless you could use it to explain to kids different orders of infinity). While Feynman was beat known for his Nobel-winning work in quantum electrodynamics and subsequent achievements in particle physics, Gleick traces the many byways in the physicist's career: his study of helium superfluidity; his brief flirtation with molecular biology; his interest in sleep and dreams. And then there were his involvement with the Manhattan Project; the loss to tuberculosis of his beloved Arline; his relentless womanizing; his eventual marriage to Gweneth--the English woman he met on a beach in Geneva and arranged to bring over as his domestic servant; his children; his lectures; his refusal to take graduate students; his skepticism about grand unified theories; the Challenger disaster. Gleick weaves all these threads into a rich portrait of an imperfect, complex, to-his-own-self-and-to-science-be-true figure, loved and admired, yet elusive.