Matthiessen was invited, in 1979, to join what the sponsor called "the last safari into the last wilderness," namely the Selous Game Preserve, largest remaining wild-life sanctuary on the continent, and to extend the hunt with a walk into territory untrodden by white men before, in the company of an ex-gamewarden, Brian Nicholson, and the eminent photographer, Baron Hugo von Lawick. As anyone who has read The Snow Leopard will recall, Matthiessen combines the exhaustive knowledge of the naturalist (he knows the names of everything—bird, bush and mammal!) with a poet's response to farout landscapes. Since the country into which he trekked on this occasion is in one of the new African republics, Tanzania, his book [Sand Rivers] has the twin appeal of a travelogue and a political footnote. Matthiessen confesses to being a sentimental American who would like to argue the cause of Africa for the black...