We show how classical spacetime emerges from quantum gravity through the study of a quantum FRW cosmological model coupled to a free massive scalar field using a new asymptotic expansion method of the Wheeler - DeWitt equation. It is shown that the coherent states of the nonadiabatic basis of a particular generalized invariant give rise to the quantum back reaction of the matter field, which is proportional to the classical energy, and the Einstein - Hamilton - Jacobi equation with a matter field becomes equivalent to the classical Einstein equation.