A so-so 1954-1974 retrospective--eleven stories and one essay, originally printed in magazines and anthologies--from an author who (with Frank Robinson) has lately switched to such wide-screem doomsday screamers as The Glass Inferno and The Prometheus Crisis. After each tale comes an author's Afterword; and there are also bits of a running autobiography (following Scortia's career through the army, into rocketry and film scripting), which is often more interesting than the stories. The early works are unpolished but imaginative, including a novelette about cyborgs and starships, stories about psi-powered children (Ã la van Vogt) or abortive trips to the moon, and a fable about a boy and his dragon. The later pieces, equally wide in scope but emotionally uncontrolled, feature: a human messiah saving an alien race from self-destruction; phone calls from the past; clones; sexual hangups; and a long, morbid variation on the Tithonus myth. Plus: a well-argued essay on sf as the art of creating imaginary scientific experiments. Sadly and strangely, however, editor Zebrowski has for some reason omitted Scortia's comic masterpiece, ""The Bomb in the Bathtub"" (Scortia himself refers to it twice); without it Scortia's ""best of"" is incomplete. And, in any case, this is an energetic but less than incisive collection from a writer who has never been one of sf's leading lights.