Since ancient times, human beings have connected beauty with symmetry. In science, this correlation is found in many areas, from the fundamental laws of physics to the products of modern chemistry. However, it seems emphasise the deadness of perfect symmetry or the dis-symmetry makes the phenomenon. As well known, most molecules will become less symmetrical as substitutions take place. Here, the authors turn to a consideration of how to describe the effect of this kind of imperfect symmetry on molecular properties.