 Although advocates of the canonical approach often accuse string theorists of relying too heavily on classical background spacetime, the canonical approach does something which is arguably quite similar, in that one begins with a theory that conceives time-evolution in terms of evolving some data specified on an a priori given spacelike surface, and then quantizing the theory. However, this does not imply any breaking of spacetime diffeomorphism invariance (or general covariance) since the constraints that must be satisfied by the data on the slice mean that the physical observables of the theory will be independent of whatever foliation one chooses. However, the problem is that if spacetime is quantized along these lines, the assumption (of evolving then quantizing) does not make sense in anything but an approximate way. That is, the evolution does not generate a classical spacetime! Rather, solutions will be wave-functions (solutions of some Schrödinger-type equation). This issue in particular is decidedly neglected in both the physical and philosophical literature (but see Isham, 1993), and there is more that might be said. We return to the issue of time in quantum gravity below.