An interesting observation was reported by Corrigan-Sasaki that all the
frequencies of small oscillations around equilibrium are " quantised" for
Calogero and Sutherland (C-S) systems, typical integrable multi-particle
dynamics. We present an analytic proof by applying recent results of
Loris-Sasaki. Explicit forms of `classical' and quantum eigenfunctions are
presented for C-S systems based on any root systems.