Habit is stronger than reason.

Skepticism is the chastity of the intellect...

The Soul is the voice of the body's interests.

Logic, like language, is partly a free construction and partly a means of symbolizing and harnessing in expression the existing diversities of things; and whilst some languages, given a man's constitution and habits, may seem more beautiful and convenient to him than others, it is a foolish heat in a patriot to insist that only his native language is intelligible or right.

Friends need not agree in everything or go always together, or have no comparable other friendships of the same intimacy.

Even the most inspired verse, which boasts not without a relative justification to be immortal, becomes in the course of ages a scarcely legible hieroglyphic; the language it was written in dies, a learned education and an imaginative effort are requisite to catch even a vestige of its original force. Nothing is so irrevocable as mind.

It is a pleasant surprise to him (the pure mathematician) and an added problem if he finds that the arts can use his calculations, or that the senses can verify them, much as if a composer found that sailors could heave better when singing his songs.