  It is well known in classical mechanics that, the frequencies of a periodic
system can be obtained rather easily through the action variable, without
completely solving the equation of motion. The equivalent quantum action
variable appearing in the quantum Hamilton-Jacobi formalism, can, analogously
provide the energy eigenvalues of a bound state problem, without having to
solve the corresponding Schr\"odinger equation explicitly. This elegant and
useful method is elucidated here in the context of some known and not so well
known solvable potentials. It is also shown, how this method provides an
understanding, as to why approximate quantization schemes such as ordinary and
supersymmetric WKB, can give exact answers for certain potentials.
