Packing muscle onto the physique is both an art and a science. It is a science because there are certain known, quantified factors that can be utilized to aid in growth. For instance, the amount of calories in a gram of protein or fat are known factors that can be used and relied on. Many of the aspects of training have already been defined and quantified by previous generations. There are certain rules within the system of bodybuilding that have already been discovered. There is no need to re-invent the wheel for many areas of training for mass muscle production.