Just noting this as it seems relevant to several of our discussions, including (1) how there are two feelings, (2) whether we can feel pleasure and pain at the same time, (3) whether we measure feeling in total, offsetting discrete feelings one against the other, etc.
This is Lucretius Book Three, approximately line 112 (1743 Edition):
First then, I say, the mind of man (which we commonly call the soul) in which is placed the conduct and government of life, is part of man no less than the hand, the foot, the eyes, are parts of the whole animal; though many of the philosophic herd have fancied that the sense of the mind is not fixed to any particular part, but is a sort of vital habit of the whole body, which the Greeks call Harmony; and thence flows all our sense, and the Mind has no particular place for its abode. As when we say health belongs to the body, yet it is no part of the body that is in health, so no particular part, they tell us, is the residence of the mind. But in this they seem to be egregiously wrong, for often when some visible part of the body suffers pain, we feel pleasure in some other part to us unseen; and the contrary often happens in its turn, that a man disturbed in mind is perfectly well all over his body, in the same manner as when a man has the gout in his foot, his head at the same time is free from pain.