Four major themes are central to Larry Niven's writing. The first of these concerns human relations with alien civilization, especially the first human contact. Often a human character will gain insight into individual aliens or even into alien civilization itself, but frequently such insight does not prevent the aliens from posing a grave threat to mankind. A second theme arises in Niven's studies of limited psychic power in humans, with the emphasis on the adjective "limited." Unlimited psychic powers might make for dull stories, of course, but the deeper reason for this restriction may be that Niven doubts the existence of psychic power strong enough to make a major difference in the lives of men. He can, and does, imagine extraterrestrials with great psychic abilities, but suspects that if such powers were truly human potentials they would have influenced human history more obviously than they have. He shows...