Full Idea
Things then are good and evil only in reference to pleasure and pain.
Gist of Idea
Things are good and evil only in reference to pleasure and pain
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.20.02)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.229
A Reaction
This is presumably the seeds of utilitarianism, and is evidently at the core of empiricism. In "Gorgias" Socrates explained why it is wrong.