To learn new habits is everything, for it is to reach the substance of life. Life is but a tissue of habits.

Self-interest is an inexhaustible source of convenient illusions. The number of beings who wish to see truly is extraordinarily small.

The philosopher aspires to explain away all mysteries, to dissolve them into light. Mystery on the other hand is demanded and pursued by the religious instinct; mystery constitutes the essence of worship, the power of proselytism.

To know how to suggest is the great art of teaching. To attain it we must be able to guess what will interest; we must learn to read the childish soul as we might a piece of music. Then, by simply changing the key, we keep up the attraction and vary the song.

Philosophy means the complete liberty of the mind, and therefore independence of all social, political or religious prejudice... It loves one thing only... truth.

War is a brutal and fierce means of pacification; it means the suppression of resistance by the destruction or enslavement of the conquered.

I wonder whether I should gain anything by the attempt to assume a character which is not mine. My wavering manner, born of doubt and scruple, has at least the advantage of rendering all the different shades of my thought, and of being sincere. If it were to become terse, affirmative, resolute, would it not be a mere imitation?