Modern History Sourcebook posts this 1892 essay that offers a succinct summary of Haeckel's pantheist beliefs.

Creationist page attempts to expose some of Haeckel's efforts to doctor pictures in order to prove his evolutionist theories.

Article reprinted from the 1911 Encyclopedia Britannica offers a detailed account of the life and works of this German biologist and philosopher.

Essay discusses the history of naturalistic pantheism, also called religious atheism, and examines Haeckel's ideas and their influence on Nazism.

Read about this evolutionist's views on how the environment directly effects organisms, or peruse his biography.

Explains Haeckel's main theory about the role of evolution in biological development.