Pi by Robert Morgan

The secret relationship
of line and circle, progress
and return, is always known,
transcendental and yet
a commonplace. And though
the connection is written
it cannot be written out
in full, never perfect, but
is exact and constant, is
eternal and everyday
as orbits of electrons,
chemical rings, noted here
in one brief sign as gateway
to completed turns and
the distance inside circles,
both compact and infinite.