Unity through Continuation

Continuation is a line or edge that continues from one form to another, allowing the eye to move smoothly through a composition, and this can also attribute to unity.

This device is much more subtle than that of repetition and proximity. As you can see in this Degas painting, the dancer on the left is leaning towards the next dancers, then the rail they are stretching on continues to the dancers on the other side of the painting and the bottom right dancer's leg is stretched towards the dancer on the far left, which causes the eye to travel full circle through the composition.