Letter 92 (§6)

“If you are not contented with only that which is honourable, it must follow that you desire in addition either the kind of quiet which the Greeks call “undisturbedness,” or else pleasure. But the former may be attained in any case. For the mind is free from disturbance when it is fully free to contemplate the universe, and nothing distracts it from the contemplation of nature. The second, pleasure, is simply the good of cattle. We are but adding the irrational to the rational, the dishonourable to the honourable. A pleasant physical sensation affects this life of ours;”