Mosaic II, lithograph, 1957.

“… They could also only be created after years of training with regular fillings. The recognizability of their components as natural objects plays an even more important role. Enjoyment in the difficult game, without symbolic ulterior motives, was the only real reason for their creation…
The rectangularity of the entire surface is the only regularity that is still present here. Of the inner figures, only a few are bordered by four surrounding ones. The immediate environment of the frog consists of two figures; the guitar is bounded by three, the rooster by five, and the ostrich (if it is one) by six. The total number is only apparent after careful counting. ” ~ M.C. Escher, Grafiek en Tekeningen.