For the novice in science fiction, "seetee" means contra-terrene, referring to matter in which the positive and negative charges are reversed from the familiar earthly pattern. Mr. Stewart, the great exploiter of the theme, published a very bad novel a year or so ago called "Seetee Shock"; he's now redeemed himself by rewriting into a good book ["Seetee Ship"] several of the magazine stories in which he first introduced the notion. Better editing would have helped the rewrite; there's still too much clumsy writing and oversimplified characterization. But the ingenuity of the contra-terrene mechanisms, the rousing melodrama of struggles in the asteroid belt, and the fine complex reversals of time and causation make this one of the best recent examples of the pure unalloyed space-opera.