What are the three main techniques for creating unity in a piece of artwork?

To create Unity in a piece of art, everything needs to look as if it belongs together. There are lots of ways to achieve unity within a work of art. Three ways to achieve unity are by proximity, repetition, and continuation. Proximity implies that elements placed close together have a better chance of looking as though they belong together or are part of the same group. Repetition implies that elements which repeat within a work of art will tend to unify a design. Continuation is a way to achieve unity when one element of the composition is connected, usually by a line or edge, to another element in the composition.

i think these large heads represent their gods and i do think they were worshiped by the people. if there was only one head and no heads around it i think it would be monotheistic but if there are several heads close to each other it could be polytheistic.