RUPERT BROOKE by Christopher Hassall. 557 pages. Harcourt, Brace & World. $8.75.
"Why," he wondered as a boy, "do we always know someone everywhere?" The answer was simple. Rupert Brooke grew up among Top People in an era when no other kind counted in England. As a kid he built sandcastles with Virginia Woolf. Other adoring contemporaries included Darwin's granddaughters, Keyneses, Stracheys and most of the other young Britons who were to leave their mark on the times. As the late Christopher Hassall makes clear in this massive, kindly biography, Rupert Brooke had...