Science is facts; just as houses are made of stone, so is science made of facts; but a pile of stones is not a house and a collection of facts is not necessarily science.

Space is only a word that we have believed a thing.

Exactness cannot be established in the arguments unless it is first introduced into the definitions.

Sociology is the science which has the most methods and the least results.

Astronomy is useful because it raises us above ourselves; it is useful because it is grand. It shows us how small is man's body, how great his mind, since his intelligence can embrace the whole of this dazzling immensity, where his body is only an obscure point, and enjoy its silent harmony.

To doubt everything or to believe everything are two equally convenient solutions; both dispense with the necessity of reflection.

The mathematical facts worthy of being studied are those which, by their analogy with other facts, are capable of leading us to the knowledge of a physical law.

Absolute space, that is to say, the mark to which it would be necessary to refer the earth to know whether it really moves, has no objective existence.

Science is facts.

Facts do not speak.