Enantiomorphy

Abstract

In the previous chapter we noted that the mesh in the 236 system is a right triangle having angles of 30° and 60°. Adjacent meshes cannot be made to overlap each other completely by rotation in the plane; one needs to be flipped over out of the plane to be brought into coincidence with its neighbor. The operations which we have considered so far, rotation and translation, do not relate motifs which need to be flipped over to be brought into coincidence with each other. In Figure 7-1 we see two motifs which are mutually congruent but which are not related by rotation in the plane or by translation. They are, in point of fact, each others’ mirror images; we call them oppositely congruent. Flipping one out of the plane to bring it into coincidence with its mirror image is called reflection ; an object and its mirror image are called a pair of enantiomorphs . (En-anti-o-morph in Greek means “in opposite form.”)