|Untitled (Ocean) by Vija Celmins|
The drawing has a lot of unity with how each element including the shadows, lights, values and gradients all mix together well to produce a realistic ocean design. The elements don't argue with each other to where it loses it realism but work together to create a beautiful drawing.
Stewart, Mary. "Unity and Variety." Launching the Imagination: A Comprehensive Guide to Two-Dimensional Design. 5th ed. New York: McGraw-Hill Education, 2015. 66. Print.