To tell the story of the document that crystallized the principles and ideals of contemporary humanism is to tell the story of the origins of the humanist movement itself. Conceived from a convergence of freethought and religious liberalism at the end of the nineteenth century, born out of the global upheaval of World War I, nourished by the cultural revolutions of the 1920s, modern humanism came of age in 1933 with the publication of "A Humanist Manifesto." This statement of fifteen affirmations on cosmology, biological and cultural evolution, human nature, epistemology, ethics, religion, self-fulfillment, and the quest for freedom and social justice explicitly delineated the leading ideas and aspirations of its era.

Changing times, however, brought new challenges the rise of fascism, World War II, the spread of communism, the Cold War-with consequent calls to revise or replace the manifesto. These appeals, too, make up part of the early history of the humanist philosophy and the people who fostered its development. The Genesis of a Humanist Manifesto is therefore a chronicle of American humanism through the first half of the twentieth century, told by one of the people most responsible for its historic unfoldment.