Control over the variables is icing on the cake. Very few events ever happen in isolation from other events. There is no such thing as a mere coincidence. Having an accurate physical or mental representation of something facilitates control over it. Look alikes are alike.
Magical power is contagious.
This also works, because knowing the complete and true name of something or someone means that you have achieved a complete understanding of it's or their nature. Many of such words are names, though the meanings may have been lost or forgotten. Anything can be a person. Most weather mages personify the winds and the clouds, for example, and thus find focussing their magic on the atmosphere much easier to do. It is possible through maximum association between elements of oneself and those of another being to actually become that being, to the point of sharing it's knowledge and wielding it's power.