If brown rats spoke a human language, they would coin the term rodentism to affirm their conviction that the world is their trash can. Homo sapiens, however, is convinced, with Protagoras, that “Man is the measure of all things,” and so we invented humanism. The doctrine rests, according to Sarah Bakewell, on three principles: “Freethinking, Inquiry, and Hope.” And it is her fervent hope that we each live the one life we have with joy, curiosity, and compassion. She is an evangelist for a movement that substitutes reason for religious dogma.

In books such as and , Bakewell, she appends the “Declaration of Modern Humanism,” adopted last year in Glasgow by the General Assembly of Humanists International. “We affirm the worth and dignity of the individual and the right of every human to the greatest possible freedom and fullest possible development compatible with the rights of others,” it proclaims. But Bakewell's new volume is a more effective manifesto. It grounds its precepts about how to live in the practices of humanists from the 14th century to the present. is not quite a history as much as a chronologically ordered pantheon.