  Starting from the Lagrangian formulation of the Einstein equations for the
vacuum static spherically symmetric metric, we develop a canonical formalism in
the radial variable $r$ that is time--like inside the Schwarzschild horizon.
The Schwarzschild mass turns out to be represented by a canonical function that
commutes with the $r$--Hamiltonian. We investigate the Wheeler--DeWitt
quantization and give the general representation for the solution as
superposition of eigenfunctions of the mass operator.
