Transparency, Interpenetration

If one sees two or more figures partly overlapping one another,and each of them claims for itself the common overlapped part, then one is confronted with a contradiction of spatial dimensions. To resolve this contradiction, one must assume
the presence of a new optical quality. The figures are endowed with transparency; that is they are able to interpenetrate without an optical destruction of each other. Transparency however implies more than an optical characteristic; it implies a
broader spatial order. Transparency means a simultaneous perception of different spatial locations. Space not only precedes but fluctuates in a continuous activity. The position of the transparent figures has equivocal meaning as one sees each figure now as the closer, now as the further one. -Gyorgy Kepes, 1944