"to let it go"

Ah, here's another Mary Oliver poem. Enjoy:

In Blackwater Woods


Look, the trees
are turning
their own bodies
into pillars

of light,
are giving off the rich
fragrance of cinnamon
and fulfillment,

the long tapers
of cattails
are bursting and floating away over
the blue shoulders

of the ponds,
and every pond,
no matter what its
name is, is
nameless now.

Every year
everything
I have ever learned

in my lifetime
leads back to this: the fires
and the black river
of loss
whose other side
is salvation,

whose meaning
none of
us will ever know.
To live in this world

you must be able
to do
three things:
to love what is mortal;
to hold it

against your
bones knowing
your own life depends on it;
and, when the time comes to let it go,
to let it go.

Isn't that a perfect last line? That's what we are about: learning to let it go, whatever "it" is.