A science of all these possible kinds of space [the higher dimensional ones] would undoubtedly be the highest enterprise which a finite understanding could undertake in the field of geometry... If it is possible that there could be regions with other dimensions, it is very likely that God has somewhere brought them into being.

The more we come in contact with animals and observe their behaviour, the more we love them, for we see how great is their care of the young.

It is difficult for the isolated individual to work himself out of the immaturity which has become almost natural for him.

Human reason is by nature architectonic.

We can never, even by the strictest examination, get completely behind the secret springs of action.

The wise man can change his mind; the stubborn one, never.

A man who has tasted with profound enjoyment the pleasure of agreeable society will eat with a greater appetite than he who rode horseback for two hours. An amusing lecture is as useful for health as the exercise of the body.