Patterns that use a combination of repeated small shapes to cover a surface completely are called tessellations. Theoretically, the pattern should be able to go on forever – or at least until the person creating it runs out of space or materials.
Mathematicians have been fascinated by tessellations, and by trying to understand all the shapes that, combined, will cover an area without leaving gaps. Escher was fascinated by them too and studied and copied some of the patterns he found in the Alhambra when visiting Spain. When he began to create his own tessellations he focused on using the figures of people, animals and fish. Then he used color and figures to create a sense of movement within the pattern.
When you look at his print “Regular Division of the Plane with Birds” you find yourself looking from the black birds to the white birds and back again. The white birds seem to move forward, the black birds look as if they are falling back. Each is what the other is not, and together they create negative and positive, movement and rest.
What is essentially a flat, static pattern creates a sense of texture and movement. Another illusion.
M. C. Escher, Regular Division of the Plane with Birds
Hexagonal Tessellation (Floor, Rome) image taken by David Shay, shared under Creative Commons Attribution-Share Alike 3.0 license.