Experiment is the sole interpreter of the artifices of Nature.

Nature is the source of all true knowledge. She has her own logic, her own laws, she has no effect without cause nor invention without necessity.

Though nature grants vast periods of time for the work of natural selection, she does not grant an indefinite period; for as all organic beings are striving, it may be said, to seize on each place in the economy of nature, if any one species does not become modified and improved in a corresponding degree with its competitors, it will soon be exterminated.

Man selects only for his own good: Nature only for that of the being which she tends.

What a book a devil's chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel work of nature!

I do not see why man should not be just as cruel as nature.