Escher takes you down Strange loop (or is he taking you up)
Two-step Strange Loop
More Escher pictures
Implicit in the concept of Strange loops is the concept of infinity, since what else is a loop but a way of representing an endless process in a finite way? And infinity plays a large role in many of Escher's drawings.
In some of his drawings, one single theme can appear on different levels of reality. For instance, one level in a drawing might clearly be recognizable as representing fantasy or imagination; another level would be recognizable as reality. These two levels might be the only explicitly portrayed levels. But the mere presence of these two levels invites the viewer to look upon himself as part of another level; the viewer cannot help but getting caught up in Escher's implied chain of levels, in which, for any one level, there is always another level aboe it of greater "reality", and likewise, there is always another level, "more imaginary" than it is.