There is a certain amount of science to audio engineering , what I mean is that you have to make the sound fit into the medium, so you have to learn the limits of your medium, speakers and amplifiers. That’s what mastering is really all about. In fact, at first, mastering engineers were just that, engineers. All they did was make sure that the sounds they were given fit into the medium, but over time, mastering developed into the art that it is today, so as audio engineers we have to study both the science and the art. The same thing applies to being a mix engineer, but I think the art is more important in mixing, while in mastering the science is more dominant.

Advanced Audio Mixing: The Art and Science