Thus, anything that can be identified is a resource (i.e., you can use everything for something) and URIs are one means (and one that has been found very useful) for providing that identity.
I think there's a slight confusion here. It is decidedly *not* a name (which URIs are) that provides the identity. Granted, URIs are meant to be *identifiers* which suggests that at any given time they name one and only one thing. Rather, it is the primitive fact that books are individuable at all, for example, that allows them to be so named. There's the identity.