Full Idea
Unity of substance does not comprehend all sorts of identity, and will not determine it in every case.
Gist of Idea
Not all identity is unity of substance
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.27.07)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.332
A Reaction
He has been discussing living things, and persons. If identity is seen functionally, then presumably substance can change while identity is retained. But we must not slide into equating substance [ousia?] with matter [hule?].