FIGURE 22. Relativity, by M. C. Escher (lithograph, 1953).symbols" of a formal system. This ultimate escape route is an example of a
"U-mode" response-a Zen attitude towards symbolism.)
So we are forced, by the hierarchical nature of our perceptive process-
es, to see either a crazy world or just a bunch of pointless lines. A similar
analysis could be made of dozens of Escher pictures, which rely heavily
upon the recognition of certain basic forms, which are then put together in
nonstandard ways; and by the time the observer sees the paradox on a high
level, it is too late-he can't go back and change his mind about how to
interpret the lower-level objects. The difference between an Escher draw-
ing and non-Euclidean geometry is that in the latter, comprehensible
interpretations can be found for the undefined terms, resulting in a com-
(^98) Consistency, Completeness, and Geometry