Full Idea
The same water may produce the idea of cold by one hand and of heat by the other; ...but figure never produces the idea of a square by one hand which has produced the idea of a globe by the other.
Gist of Idea
Hands can report conflicting temperatures, but not conflicting shapes
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.08.21)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.139
A Reaction
I find this to be a thoroughly convincing argument in favour of the primary/secondary distinction, despite the later objects of Berkeley, Hume and Kant. One might add colour blind people reporting differently from the rest of us.