Happiness consists in frequent repetition of pleasure

A man's knowledge may be said to be mature, in other words, when it has reached the most complete state of perfection to which he, as an individual, is capable of bringing it, when an exact correspondence is established between the whole of his abstract ideas and the things he has actually perceived for himself. His will mean that each of his abstract ideas rests, directly or indirectly, upon a basis of observation, which alone endows it with any real value; and also that he is able to place every observation he makes under the right abstract idea which belongs to it.

We can regard our life as a uselessly disturbing episode in the blissful repose of nothingness.

Philosophy ... is a science, and as such has no articles of faith; accordingly, in it nothing can be assumed as existing except what is either positively given empirically, or demonstrated through indubitable conclusions.

Patriotism, when it wants to make itself felt in the domain of learning, is a dirty fellow who should be thrown out of doors.

The principle of contradiction establishes merely the agreement of concepts, but does not itself produce concepts.

To call the world God is not to explain it; it is only to enrich our language with a superfluous synonym.