INFINITY: One of Escher's ambitions was to represent infinity
in a confined space, and in doing so, he employs hyperbolic geometry. That
is, on a hyperbolic plane, points infinitely far way are thought of as within
a circle, which is the hyperbolic world. Geometric form is consistent within
the plane, but the distances are distorted. The circumference is infinitely
far away from the center, and one might consider the perpective change when
looking upon a shpere to understand how the distance becomes increasingly
more distorted as we move from center to circumference. Circle Limit III
is an excellent example of this kind of representation.
Escher also represents infinity from the reverse direction, using a mathematical
procedure known as inversion. Inversion represents all points in two-dimensional
space in a circle such that as a point in space gets farther from the circle's
circumference, the corresponding point in the inversion circle approaches
the center much the way an asymptotic line approaches a limit. Escher basically
inverts equiangular spirals, which we see here: