M.C. Escher was a Dutch graphic artist, most recognized for spatial illusions, impossible buildings, repeating geometric patterns (tessellations), and his incredible techniques in woodcutting and lithography.
escher
duality
The idea of a duality such as air and water can be expressed in a picture by starting from a plane-filling design of birds and fish; the birds are "water" for the fish, and the fish are "air" for the birds. Heaven and Hell can be symbolized by an interplay of angels and devils. There are many other possible pairs of dynamic subjects--at least in theory, for in most cases, their realization meets with insuperable difficulties.
M.C. Escher