Peter Matthiessen is one of the important wilderness writers of our time. His The Tree Where Man Was Born … is a masterpiece of understated prose and exacting description. Matthiessen has clearly trained himself to see as a naturalist….

The Snow Leopard is based on the journal Matthiessen kept during his trek with the field biologist George Schaller to the Crystal Mountain, in upper Nepal, in 1973…. The purpose: to observe the November rut of the Himalayan blue sheep in order to determine whether this little-known species is related to the extinct common ancestor of the goat and the sheep. They also hoped to glimpse another animal, so rarely seen that it is almost a myth: the snow leopard, which comes to stand in Matthiessen's mind for a grail of fulfillment.

For Matthiessen's journey out of time is not only a naturalist's venture into one last wilderness but also an...