Get fifteen sf writers together, as Bretnor does here, and you'll get eighteen opinions on what the blasted creature is and how to go about writing it. Poul Anderson celebrates sf's ability to hold up images of the heroic and marvelous to a world that has lost sight of these qualities; Katherine MacLean talks movingly of sf communication with aliens as a window on our own sensory and conceptual prisonhouse. On a more practical level, there are some testimonials to the virtues of knowing what you're talking about--or being careful and consistent enough to look as if you do--before tackling scientific breakthroughs (Hal Clement) or future social structures (Jerry Pournelle). Norman Spinrad lays down some provocative suggestions for fruitful manipulation of the ""rubber sciences""; Theodore Sturgeon and Frank Herbert suggest the imaginative rewards of examining the unexamined biological or economic or statistical assumptions behind the most ""obvious"" social or ethical values. Although this can't be read as a how-to manual, there are some sane suggestions about the mysteries of agents, publishers, and self-addressed stamped envelopes (Frederik Pohl), and a long, loud, cheerful piece about putting together an sf screenplay and peddling it (Harlan Ellison). A companion to Bretnor's 1973 colloquium Science Fiction: Today and Tomorrow.