Natural-history writer David Petersen"s Heartsblood is not so much about hunting, although that controversial subject is an important part of the book, as is a lively, deeply intelligent discussion of what it means to be a human animal aware of what lies outside. Petersen suggests that a true engagement with the natural world requires a keen knowledge of its workings--of how water flows, of how animal populations wax and wane--and a recognition of the realities of life and death. An avid fisherman and hunter, Petersen has little patience with the yahoos who blast at anything in sight, those thoughtless persons who have given hunting a bad name. Neither does he suffer lightly those who maintain that hunting is morally wrong, for, he insists, in the absence of natural predators, hunters act as a necessary brake on overpopulation, which can lead only to suffering. He has little use for expensive gear, for GPS systems and top-of-the-line weapons, nor for most hunting magazines, which, he says, cater to just those yahoos with a taste for fancy goodies, and which he deems "greedy and increasingly immoral." With all those peeves and qualifications, it would not be out of place for Petersen to assume a grumpy air. For the most part, however, he does not; he is cordial to those who disagree with his views, which he carefully backs with biological facts, philosophical and anthropological interpretations, and reflections gathered from a half-century"s experience in the wild. His book deserves a wide audience, and the ideas within it merit much discussion as thoughtful men and women everywhere do what they can to protect what little is left of nature--a struggle in which hunting, Petersen holds, can play an important part. --Gregory McNamee