Not Smullyan the puzzler (What Is the Name of This Book?, The Lady or the Tiger?) but Smullyan the philosopher. . . though, with metaphysical discussions turning into conundrums and antinomies, the distinction may be more quantitative than qualitative. These diverse pieces address almost all the major questions that have traditionally concerned philosophy: ontology, epistemology, ethics, logic, metaphysics--with some emphasis on the nature of reality and extended reflection on human destiny. Here as elsewhere, however, Smullyan has a compelling way with words. He can condense time-honored arguments and esoteric positions into a few clear expository paragraphs or the sentences he lets his protagonists speak in his several dialogues. Alternatively, he provides analogies or examples. He even gives a one-page proof of Godel's theorem using a few Ps, Ns, and Rs that will be familiar to students of logic. And of course there are the jokes, anecdotes, riddles, and aphorisms that punctuate the prose, giving the reader a breather or a point to ponder. (A clever list of self-annihilating sentences--attributed to computer scientist saul Garn--includes: ""Before I began speaking, there is something I would like to say."") The title and penultimate piece deals with a long-ago metaphysician who is projected into contemporaneity to ponder anew the question, ""What keeps the earth up?"" This is the foil for Smullyan's final opportunity to trot forth the positions of many schools and, in the last piece (""Afterthoughts""), to suggest where he himself stands. Solomon-like, Smullyan notes the value of trying to model someone else's position in one's own framework rather than setting out to demolish it. He finds value also in pondering ""meaningless"" or ""false"" statements, for they can give rise to fruitful ideas, He confesses to a liking for certain Zen positions and speaks sympathetically of the ""enlightened solipsist"" who believes that his neighbor is himself. To unravel that conundrum requires an excursion into the book--it's well worth it.