Pick of the paperbacks; E. M. Forster: A Life, by P. N. Furbank. New York: Harvest/Harcourt Brace Jovanovich. $8.95.

This authorized biography is rich in correspondence, anecodotes, interviews, background and analysis. it is a definitive work -- answering questions as only a friend of Forster's could.

As it makes compassionately clear, to fully understand Forster is to know about his homosexuality; his attachment to his mother, and his quest for enduring male companionship.

It's a sad story filled with explicit descriptions of flirtations and affairs , with guilt, secrets, and repressions caused by Forster's thwarted need to announce his homosexuality in his writings. But it is also a story with affir mations and rewards, for Forster and for readers.