Principles: Balance and Contrast
Balance-Imagine if you had a backpacking trip with one other person, and they made you carry all of the group stuff in addition to your own. You would be angry and want to make them carry an equal amount of stuff as you. This would be balance, when two things are equal on both ends.
Contrast-In a car lot, all of the Toyota Prius’ are the same size and look normal. But imagine if you were sitting in your embarrassingly little Prius, suddenly a Hummer pulls up next to you. It is twice the size of your Prius and that is contrasting, when you compare two things like that.