Through much of his career, Krutch was a teacher of criticism at Columbia University and a drama critic for The Nation. But then respiratory problems led him to early retirement in the desert near Tucson, Arizona. He loved the desert and there turned to biology and geology, which he applied to maintain a consistent, major theme found in all of his writings, that of the relation of humans and the universe. Krutch subsequently became an accomplished naturalist.

Readers can find the theme of man and universe in Krutch's early work, for example The Modern Temper (1929), and in his later writings on human-human and human-nature relationships, including natural history—what Rene Jules Dubos described as "the social philosopher protesting against the follies committed in the name of technological progress, and the humanist searching...