Newton had it right centuries ago
with his three physical laws
of motion
            of force
                        of mass,

three stool legs on which to stand 
quantum mechanics, relativity and string.  

Our human bodies are like bicycles,
upright by balancing
gravity
            angularity
                        velocity.

Our toes press in ten directions all at once,
forces which move us back and forth,
rocking ever so slightly as our muscles flex and un-flex
beneath the fascia and dermis.  

Always in motion, chest rising,
heart beating, eyes blinking, ears burning.
We do not stand on two,
but on ten
            plus two    
                        plus a thousand others.  

But three we lean on, wrap
our arms around backs, link elbows,
crisscross knees and fingers in our conjoining.

That we procreate more than the two of us,
more than existing in a two dimensional land
unable to hold water in the cup of our hand.  

We are three so that we can pinpoint
location and trajectory
of we.