Full Idea
Some things are not naturally pleasant but become so, either through injury, or through habit, or through congenital depravity.
Gist of Idea
Some things are not naturally pleasant, but become so through disease or depravity
Source
Aristotle (Nicomachean Ethics [c.334 BCE], 1148b16)
Book Reference
Aristotle: 'Ethics (Nicomachean)', ed/tr. ThomsonJ A K/TredennickH [Penguin 1976], p.237
A Reaction
We might say that there are indeed 'unnatural pleasures' (e.g. sadism?), but still have to admit that we have no clear way of distinguishing the natural from the unnatural. What about gambling? Or watching horror films?