M.C. Escher was a graphic artist renowned for his lithographs, mezzotints and woodcuts inspired by mathematics. Born in 1898, his first remarkable work came in 1937 with the print Still Life and Street, a piece that utilized the play on perspective that would become known as "impossible reality". The edge of the desk in the foreground continues deep into the drawing and melds into a street and books sitting on it seem to be leaning against the buildings behind them.



An instantly recognizable Escher work is Drawing Hands, produced in 1948. The lithograph shows a paradox (a common theme to his works) of two drawn hands "rising" from their page to draw their counterpart, bound at the wrists to the paper below them. The paradox arises from the fact that each of the hands is being created simultaneously by the other.

Sky and Water I, a woodcutting from 1938, is a regularly divided plane alternating the darkened images of birds with the light images of fish, locking together like puzzle pieces. The animals form a diamond shape with the birds being more obvious to the eye at top, the fish at the bottom and sharing the attention (depending on which shade the eye decides to focus on) in the center. Escher said, "We associate flying with sky, and so for each of the black birds the sky in which it is flying is formed by the four white fish which encircle it. Similarly swimming makes us think of water, and therefore the four black birds that surround a fish become the water in which it swims." The work is often used in art, science and mathematics courses to show the concept of visual perception.

Relativity, a 1953 lithograph, combines the theme of paradox with another common Escher theme- the staircase. In Relativity, the laws of gravity are ignored in favor of rooms and staircases that are turned in every direction. The inhabitants of this world are going about their daily business (eating, socializing, walking, etc.) as if nothing is amiss. But the "people" are dressed in the same clothing and have oddly shaped heads. The rooms that these people are in have gravity maintained within them regardless of its position. The staircases lead from these rooms and also follow the laws of gravity in relation to the rooms it accesses. But since more than one room applies to each staircase, and those rooms are gravitationally irrelevant to one another, the staircases have two sides and somewhat abstract. It has perhaps one of Escher's most famous works and has been referenced numerous times in other media sources, including the final showdown scenes in the children's film Labyrinth.

The Ascending and Descending, a lithograph printed in 1960, shows an enormous building whose roof is a never-ending staircase. Identically clothed men appear in two separate lines on the staircase, one going up and the other down. There are two people away from that grouping- a lone figure in the courtyard and another on the lower staircase. Instead of using relative proportions for an illusion of depth, Escher utilizes conflicting proportions to highlight his beloved paradoxes.