Let mental culture go on advancing, let the natural sciences progress in even greater extent and depth, and the human mind widen itself as much as it desires: beyond the elevation and moral culture of Christianity, as it shines forth in the Gospels, it will not go.

Our hands we open of our own free will, and the good flies, which we can never recall.

First and last, what is demanded of genius is love of truth.

Who strives always to the utmost, him can we save.

There is not a single outward mark of courtesy that does not have a deep moral basis.

Most pioneers are at the mercy of doubt at the beginning, whether of their worth, of their theories, or of the whole enigmatic field in which they labour.

Man... knows only when he is satisfied and when he suffers, and only his sufferings and his satisfactions instruct him concerning himself, teach him what to seek and what to avoid. For the rest, man is a confused creature; he knows not whence he comes or whither he goes, he knows little of the world, and above all, he knows little of himself.