Full Idea
Fundamentally, pleasure is a sense of perfection, and pain a sense of imperfection.
Gist of Idea
Pleasure is a sense of perfection
Source
Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21)
Book Reference
Leibniz,Gottfried: 'New Essays on Human Understanding', ed/tr. Remnant/Bennett [CUP 1996], p.194
A Reaction
A bit odd, but I like the idea that there is an intellectual aspect to even the most visceral feelings.