The most heated defenders of a science, who cannot endure the slightest sneer at it, are commonly those who have not made very much progress in it and are secretly aware of this defect.

It is said that truth comes from the mouths of fools and children: I wish every good mind which feels an inclination for satire would reflect that the finest satirist always has something of both in him.

Delight at having understood a very abstract and obscure system leads most people to believe in the truth of what it demonstrates.

The human tendency to regard little things as important has produced very many great things.

Honest unaffected distrust of human abilities under all circumstances is the surest sign of strength of mind.

Nothing puts a greater obstacle in the way of the progress of knowledge than thinking that one knows what one does not yet know.

To make a vow is a greater sin than to break one.