Man stands alone in the universe, a unique product of a long, unconscious, impersonal, material process with unique understanding and potentialities. These he owes to no one but himself, and it is to himself that he is responsible. He is not the creature of uncontrollable and undeterminable forces, but is his own master. He can and must decide and manage his own destiny.

Life of the past: an introduction to paleontology (ed. Books on Demand, 1953)