If there is anything in the world that can really be called a man's property, it is surely that which is the result of his mental activity.

Because people have no thoughts to deal in, they deal cards, and try and win one another's money. Idiots!

It is only a man's own fundamental thoughts that have truth and life in them. For it is these that he really and completely understands. To read the thoughts of others is like taking the remains of someone else's meal, like putting on the discarded clothes of a stranger.

Noise is the most impertinent of all forms of interruption. It is not only an interruption, but also a disruption of thought.

In our early youth we sit before the life that lies ahead of us like children sitting before the curtain in a theatre, in happy and tense anticipation of whatever is going to appear. Luckily we do not know what really will appear.

That human life must be some kind of mistake is sufficiently proved by the simple observation that man is a compound of needs which are hard to satisfy; that their satisfaction achieves nothing but a painless condition in which he is only given over to boredom . . .

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