Ernst Haeckel

Both of these branches of evolutionary science, are, in my opinion, in the closest causal connection; this arises from the reciprocal action of the laws of heredity and adaptation.

The real cause of personal existence is not the favor of the Almighty, but the sexual love of one's earthly parents.

Politics is applied biology.

By ecology we understand the total science of the connections of the organism to the surrounding external world.