It is easy to utter what has been kept silent, but impossible to recall what has been uttered.

Demosthenes, when taunted by Pytheas that all his arguments "smelled of the lamp," replied, "Yes, but your lamp and mine, my friend, do not witness the same labours.

Socrates said he was not an Athenian or a Greek, but a citizen of the world.

Education and study, and the favors of the muses, confer no greater benefit on those that seek them than these humanizing and civilizing lessons, which teach our natural qualities to submit to the limitations prescribed by reason, and to avoid the wildness of extremes.

The omission of good is no less reprehensible than the commission of evil.

To do an evil action is base; to do a good action without incurring danger is common enough; but it is the part of a good man to do great and noble deeds, though he risks every thing.

And Archimedes, as he was washing, thought of a manner of computing the proportion of gold in King Hiero's crown by seeing the water flowing over the bathing-stool. He leaped up as one possessed or inspired, crying, "I have found it! Eureka!".