Metaphysical conceits are a thing of the past. Now with moon shots and interstellar probes, a writer really in tune with his age has to think of scientific conceits, or better yet, treat mathematical formulate, or theories and equations from physics, as if they were "characters" gamboling about the universe, beaming and burping through the void, carrying on the most enlightened (though not necessarily enlightening) conversations:" 'Ahal' I said. 'Why don't we play at flying galaxies?' 'Galaxies?' Pfwfp suddenly brightened with pleasure. 'Suits me. But you. . . you don't have galaxy!' 'Yes, I do. . ." ' Italo Calvino offers many similar exchanges, his tales being extraordinary and brilliant (if you like them; tiresome and thin, if you don't) variations on the whole spectrum of evolutionary transformations, contractions, and expansions that have affected time and space since whatever your version of genesis happens to be. Calvino is a witty and fanciful fellow who enjoys linguistic pirouettes somewhat in the manner of Nabokov, but he lacks the latter's commanding personality, and he relies too heavily on the pathetic fallacy (the illusion that external objects have human feelings), so we find his simple cellular creatures telling us "When I was a kid, the only playthings we had in the whole universe were the hydrogen atoms. . . ." etc. etc. For science fiction devotees, in any case, clearly the most sophisticated item yet from that genre.