What is this poem talking about. And I especially need to know whats unique about the structure of it. Like word placement and stuff...

"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."

- Mary Oliver, "In Blackwater Woods"