In Black Body radiation, Planck's law has a postulate saying

The wall of black body contains oscillators of all possible frequencies,ν.

There is one more postulate which says

The energy of these oscillators is not continuous but discrete valued.

Of course the second one is very well known but doesn't it contradict the first one? Shouldn't it mean that frequencies of vibration are quantised like maybe in case of standing waves? Please correct me if I am wrong in stating the postulates itself.