Charles Darwin (1809–1882) is a classic author whose works are in the public domain.

Charles Darwin presents his theory of natural selection — the mechanism by which species evolve over generations — backed by twenty years of meticulous observation and evidence. The most consequential scientific book ever published, and still surprisingly readable.

Darwin turns his theory of natural selection on humanity itself — exploring human evolution, sexual selection, and the implications for race, gender, and morality. More controversial than the Origin and still essential reading for anyone interested in what we are.