Thought is only a flash between two long nights, but this flash is everything.

The aim of science is not things themselves, as the dogmatists in their simplicity imagine, but the relation between things.

Mathematics is the art of giving the same name to different things.

The scientist does not study nature because it is useful to do so. He studies it because he takes pleasure in it, and he takes pleasure in it because it is beautiful. If nature were not beautiful it would not be worth knowing, and life would not be worth living. I am not speaking, of course, of the beauty which strikes the senses, of the beauty of qualities and appearances. I am far from despising this, but it has nothing to do with science. What I mean is that more intimate beauty which comes from the harmonious order of its parts, and which a pure intelligence can grasp.

Tolstoi explains somewhere in his writings why, in his opinion, “Science for Science's sake” is an absurd conception. We cannot know all the facts, since they are practically infinite in number. We must make a selection. Is it not better to be guided by utility, by our practical, and more especially our moral, necessities?

Science is built up with facts, as a house is with stones. But a collection of facts is no more a science than a heap of stones is a house.

The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful.