Full Idea
The two ideas, of a man and a centaur, supposed to be the ideas of real substances, are the one true and the other false.
Gist of Idea
If they refer to real substances, 'man' is a true idea and 'centaur' a false one
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.32.05)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.385
A Reaction
Locke says (Idea 12522) that there is probably a proposition hidden behind this. We might say that 'man' has a reference and 'centaur' does not (strictly). Is successful reference a species of truth? 'Pick out the llama' - child points - 'that's right!'
Related Idea
Idea 12522 It is propositions which are true or false, though it is sometimes said of ideas [Locke]