Full Idea
A man saw his friend die in such a room, though these have in nature nothing to do one with another, yet when the idea of the place occurs to his mind it brings the pain with it.
Gist of Idea
If a man sees a friend die in a room, he associates the pain with the room
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.33.12)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.398
A Reaction
Students of Hume think the notion of contiguity of ideas was original to Hume. Well it wasn't.