species have become in the late twentieth century. His illuminating and accessible discussion is a characteristically skillful and compelling synthesis of hard scientific theory, factual evidence, personal anecdotes, haunting reflection, and poetic prose. Loren Eiseley (1907-1977), naturalist, essayist, philosopher, and poet, won the John Burroughs Medal for best publication in the field of nature writing in 1961 for The Firmament of Time. Introducer Gary Holthaus, a freelance poet and writer, is the author of Wide Skies: Finding a Home in the West.