Although the observed effects of the laws of optics are quite complicated, their explanation turns out to be quite simple. All we have really used in everything above is the Law of Reflection and the Law of Refraction. However, we must keep in mind that in our discourse of optical systems, le mot du jour was "approximation." In this section, we will look at problems arising from using our approximate formulas, and problems that arise from physical laws. Simply put, rays from the same object point sometimes get focussed to different image points. We will refer to these problems as aberration.