When Maxwell showed that light was an electromagnetic wave it was necessary to identify some oscillator of atomic proportions to account for these waves. Henri Lorentz , considered that electrons which are normally held in an equilibrium position are capable of vibration when displaced under the influence of a restoring force. The bound electron was supposed to be the source of the electromagnetic waves of light when executing damped vibrations. It was also capable of absorbing light when the frequency of the vibration and of the light were in agreement. This was more than a hundred years ago , much before quantum mechanics was formulated , today the only difference is that the vibrations have been shifted to ions in the crystal lattice. Thus the theory of electrical conduction as it stands today is not a quantum based theory at all. This is reflected in the fact that fields in an electrical conductor still function on an action at a distance principle.