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 only a feeble picture of an unceasing and terrible war of existence which reigns throughout the whole of the living world.

Civilization and the life of nations are governed by the same laws as prevail throughout nature and organic life.

The nucleus has to take care of the inheritance of the heritable characters, while the surrounding cytoplasm is concerned with accommodation or adaptation to the environment.

We are compelled by reflection to recognize that God is not to be placed against the material world [as in Christianity], but must be placed as a 'divine power' or 'moving spirit' within the cosmos itself ... All the wonderful phenomena of nature around us, organic as well as inorganic, are only various products of one and the same original force.

Man is not distinguished from [the animals] by a special kind of soul, or by any peculiar and exclusive psychic function, but only by a higher degree of psychic activity, a superior stage of development.

It is, however, a most astonishing but incontestable fact, that the history of the evolution of man as yet constitutes no part of general education. Indeed, our so-called "educated classes" are to this day in total ignorance of the most important circumstances and the most remarkable phenomena which Anthropogeny has brought to light.

Man is not above nature, but in nature.