 The problem of time is closely connected with a general puzzle about the ontology associated with “quantum spacetime”. Quantum theory in general resists any straightforward ontological reading, and this goes double for quantum gravity. In quantum mechanics, one has particles, albeit with indefinite properties. In quantum field theory, one again has particles (at least in suitably symmetric spacetimes), but these are secondary to the fields, which again are things, albeit with indefinite properties. On the face of it, the only difference in quantum gravity is that spacetime itself becomes a kind of quantum field, and one would perhaps be inclined to say that the properties of spacetime become indefinite. But space and time traditionally play important roles in individuating objects and their properties—in fact a field is in some sense a set of properties of spacetime points — and so the quantization of such raises real problems for ontology.