Our bodies have left sides and right sides.  If you look closely, you will notice a few special places on our bodies that are neither left nor right, but serve to join the two.  For instance, the philtrum, the groove in our upper lip.  The septum between our nostrils.  The sternum from which our ribs emanate.  The spine that supports us all.

The center largely goes unnoticed but without it, left and right fly apart.