The genetic code of DNA is constructed from four different bases: adenine (A), thymine (T), guanine (G) and cytosine (C). Each base is an object defined by what it is as distinct from what it is not. However, each base pairs with only one of the other three, which we call its complement: A pairs with T and G pairs with C. If the four objects are represented as ordered pairs, then the four “what it is” and the four “what it is not” can be represented as two interpenetrating mirror opposite chiral tetrahedrons embedded in a cube. On one face A is paired with T and on the mirror opposite face, G is paired with C.
