Systems, scientific or philosophic, come and go. Each method of limited understanding is at length exhausted. In its prime each system is a triumphant success: in its decay it is an obstructive nuisance.

People make the mistake of talking about 'natural laws.' There are no natural laws. There are only temporary habits of nature.

Without deductive logic science would be entirely useless. It is merely a barren game to ascend from the particular to the general, unless afterwards we can reverse the process and descend from the general to the particular, ascending and descending like angels on Jacob's ladder.

It is the business of future to be dangerous.... The major advances in civilization are processes that all but wreck the societies in which they occur.

In formal logic, a contradiction is the signal of defeat, but in the evolution of real knowledge it marks the first step in progress toward a victory.

The defense of morals is the battle-cry which best rallies stupidity against change.

The preternatural solemnity of a good many of the professionally religious is to me a point against them.