Ontogeny re-capitulates phylogeny.

- Ernst Haeckel

Nothing is constant but change! All existence is a perpetual flux of "being and becoming!" That is the broad lesson of the evolution of the world.

- Ernst Haeckel

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

- Ernst Haeckel

Man is not above nature, but in nature.

- Ernst Haeckel

Mental differences between the lowest men and the animals are less than those between the lowest and the highest man.

- Ernst Haeckel

The whole of organic nature on our planet exists only by a relentless war of all against all. ... The raging war of interests in human society is onl…

- Ernst Haeckel

The cell never acts; it reacts.

- Ernst Haeckel

As our mother-earth is a mere speck in the sunbeam in the illimitable universe, so man himself is but a tiny grain of protoplasm in the perishable fr…

- Ernst Haeckel

Politics is applied biology.

- Ernst Haeckel