Full Idea
To say a notion is imprinted on the mind, but the mind is ignorant of it, is to make this impression nothing. ….But if the capacity of knowing be the test of innateness, all the truths a man ever comes to know will be every one of them innate.
Gist of Idea
If we aren't aware that an idea is innate, the concept of innate is meaningless; if we do, all ideas seem innate
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 1.02.05)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.50
A Reaction
The problem is, I think, that Locke is relying wholly on introspection to decide on what is innate. If you turn to Chomsky's evidence, of children learning more language than they could possibly taught, there seems to be lots of evidence.