Darwin's On the Origin of Species

Natural selection replaces divine creation as the explanation for life's diversity — the most important idea in the history of biology.

Darwin's theory of evolution by natural selection provided a mechanism for the diversity of life without requiring a designer. It remains the foundational framework of modern biology.

Perspective

Darwin didn't just change biology — he changed everything. If humans evolved rather than being specially created, then every assumption about human nature, morality, and purpose has to be renegotiated. We're still doing that negotiation 165+ years later.