An exploration--at a consistently high level of discourse--of the implications of Darwin's theory of evolution by natural selection, which extend far beyond biology. Dennett (director, Center for Cognitive Studies/Tufts Univ.; Consciousness Explained, 1991, etc.) goes directly to the crux of the natural selection controversy: its implicit denial that a divine ""first cause"" is needed to account for the origin of life. While Darwin discreetly avoided a confrontation with orthodox religion, he could not prevent the proponents of divine creation from launching preemptive attacks against his theory. Dennett takes a rationalist tack, pointing out that any theory of a creator begs the question of how life began: If complex DNA molecules cannot have come into being without a creator, must not that creator have been even more complex to have designed the molecules? He argues his points more from a philosophical and logical position than from analysis of the scientific literature on evolution, of which he openly admits only an amateur's understanding. (On the other hand, few of the critics of Darwinian selection have any deeper knowledge of the subject.) Among the fascinating subjects he brings up in passing are the laws of probability, computer simulations of evolution, and the revisionist Darwinian theories of Stephen Jay Gould and Roger Penrose. Ultimately, he contends, the Darwinian revolution's greatest achievement is the denial of the supernatural explanation of the universe, replacing it with an even more miraculous natural explanation. Readers had best be prepared to think long and hard about the points Dennett raises, but those who stay with the author will be amply rewarded for their efforts.