An anthology on three levels: 1) a collection of top-notch sf yarns; 2) a chronicle of the effect said yarns had in shaping Silverberg's own career; 3) an object lesson for today's budding sf writers. It succeeds beautifully on the first two counts, falters on the third. To mention almost at random some of the 13 grand yams here: Damon Knight's surprising and splendidly handled alien-blob-eats-people, ""Four in One""; ""Fondly Fahrenheit,"" Alfred Bester's waggish and chilling murderous android/crisis of identity; Henry Kuttner's weird triumphant-headhunter, ""Home is the Hunter""; James Blish's tour-de-force experiment in faster-than-light travel, ""Common Time""; the first part of what became Brian Aldiss' magnificent early novel, Hothouse; C.M. Kornbluth's far-future doctor's kit, ""The Little Black Bag"", Bob Shaw's quietly glowing tale about ""slow glass,"" ""Light of Other Days""; and equally fine tales from Frederik Pohl, Philip K. Dick, Jack Vance, Cordwainer Smith, Robert Sheckley, and C.L. Moore. Editor Silverberg's autobiographical contributions are thoughtful and illuminating. The instructional aspect here, though, is troublesome. As Silverberg's plodding but mostly well-aimed analyses demonstrate, these stories are nigh-perfect examples of the craft, with, at worst, microscopic flaws. However, apprentice writers who lack the young Silverberg's boundless self-confidence might well be daunted rather than inspired by such perfection. Scintillating stories, intriguing autobiography, dubious didacticism.