  It is shown - in Ashtekar's canonical framework of General Relativity - that
spherically symmetric (Schwarzschild) gravity in 4 dimensional space-time
constitutes a finite dimensional completely integrable system. Canonically
conjugate observables for asymptotically flat space-times are masses as action
variables and - surprisingly - time variables as angle variables, each of which
is associated with an asymptotic "end" of the Cauchy surfaces. The emergence of
the time observable is a consequence of the Hamiltonian formulation and its
subtleties concerning the slicing of space and time and is not in contradiction
to Birkhoff's theorem. The results are of interest as to the concept of time in
General Relativity. They can be formulated within the ADM formalism, too.
Quantization of the system and the associated Schr\"odinger equation depend on
the allowed spectrum of the masses.
