Book VIII · Chapter 48

Remember that the ruling faculty is invincible, when self-collected it is satisfied with itself, if it does nothing which it does not choose to do, even if it resist from mere obstinacy. What then will it be when it forms a judgment about anything aided by reason and deliberately? Therefore the mind which is free from passions is a citadel, for man has nothing more secure to which he can fly for refuge and for the future be inexpugnable. He then who has not seen this is an ignorant man; but he who has seen it and does not fly to this refuge is unhappy.