Let the part of thy soul which leads and governs be undisturbed by the movements in the flesh, whether of pleasure or of pain; and let it not unite with them, but let it circumscribe itself and limit those affects to their parts. But when these affects rise up to the mind by virtue of that other sympathy that naturally exists in a body which is all one, then thou must not strive to resist the sensation, for it is natural: but let not the ruling part of itself add to the sensation the opinion that it is either good or bad.