Life, individual or collective, personal or historic, is the one entity in the universe whose substance is compact of danger, of adventure. It is, in the strict sense of the word, drama. The primary, radical meaning of life appears when it is employed in the sense not of biology, but of biography. For the very strong reason that the whole of biology is quite definitely only a chapter in certain biographies, it is what biologists do in the portion of their lives open to biography.