The power of thought, the vast regions it can master.

When it was first proposed to establish laboratories at Cambridge, Todhunter, the mathematician, objected that it was unnecessary for students to see experiments performed, since the results could be vouched for by their teachers, all of them of the highest character, and many of them clergymen of the Church of England.

Protagoras did not know if the gods exist, but he held in any case they ought to be worshiped. Philosophy, according to him, had nothing edifying to teach, and for the survival of morals we must rely upon the thoughtlessness of the majority and their willingness to believe what they had been taught.

Envy ... is one form of a vice, partly moral, partly intellectual, which consists in seeing things never in themselves but only in their relations.

If a Black Death could be spread throughout the world once in every generation survivors could procreate freely without making the world too full.

No satisfaction based upon self-deception is solid, and however unpleasant the truth may be, it is better to face it once and for all, to get used to it, and to proceed to build your life in accordance with it.

If there were in the world today any large number of people who desired their own happiness more than they desired the unhappiness of others, we could have a paradise in a few years.