EXCERPT Prior to this, Kant had already allowed osteology to productively constrain cognition by emphasizing the importance of the subjective incommensurability of Left and Right in anchoring spatial orientation. He used this observation to demonstrate that our specific sense of space is a ‘form of intuition’ (rather than any necessary or independently verifiable feature of reality separate from our sensing). Thus, Kant rallies incommensurability as an illustration in order to further his overall rationalist argument. However, such Left-Right ‘enantiomorphism’—the fact that each hand is a non-superimposable mirror image of the other (an ‘incongruous counterpart’)—derives from our chiral handedness, which is a direct consequence of our anciently inherited bilateral symmetry—that is, symmetry along a sagittal, i.e. spinal, plane…