  We present detailed theoretical model of electron motion inside of an atom or
molecule when subjected to electro-magnetic wave. This theoretical model, that
we called Invicem Lorentz Oscillator Model (ILOM), contains Lorentz Oscillator
Model (LOM) as a simplified approximation. The ILOM demonstrates artificial
nature of the separation of descriptions of electromagnetic wave propagation in
media into Linear and Nonlinear Optics.
