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 framework of organic nature.

Man is not above nature, but in nature.

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

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

There is no doubt that the course and character of the feared 'European war'... will become the first world war in the full sense of the word.

Among the Spartans all newly born children were subject to a careful examination or selection. All those that were weak, sickly, or affected with any bodily infirmity, were killed. Only the perfectly healthy and strong children were allowed to live, and they alone afterwards propagated the race.

Ontogeny re-capitulates phylogeny.