The Third Body, by Robert Bly

 
The Third Body

A man and a woman sit near each other, and they do
  not long
At this moment to be older, or younger, or born
In any other nation, or any other time, or any other
  place.
They are content to be where they are, talking or not
  talking.
Their breaths together feed someone whom we do
  not know.
The man sees the way his fingers move;
He sees her hands close around a book she hands to
  him.
They obey a third body that they share in common.
They have promised to love that body.
Age may come; parting may come; death will come!
A man and a woman sit near each other;
As they breathe they feed someone we do not know,
Someone we know of, whom we have never seen.

by Robert Bly, from Eating the Honey of Words, 1999