Eloquence is heard; poetry is overheard ... All poetry is of the nature of the soliloquy.

The application of algebra to geometry ... has immortalized the name of Descartes, and constitutes the greatest single step ever made in the progress of the exact sciences.

The disease which inflicts bureaucracy and what they usually die from is routine.

It is better to be Socrates dissatisfied than a pig satisfied.

They who know how to employ opportunities will often find that they can create them; and what we can achieve depends less on the amount of time we possess than on the use we make of our time.

If opponents of all important truths do not exist, it is indispensable to imagine them and supply them with the strongest arguments which the most skillful devil's advocate can conjure up.

The philosophy of reasoning, to be complete, ought to comprise the theory of bad as well as of good reasoning.