John Wheelwright's "Any Friend to Any Friend" (Commonplace Book)

[The subtitle of this poem is an equation, but I do not know how to make blogger do proper superscript, so I am going to have to write out "squared" as a word, even though it is a superscript number 2 on the page.]

(A - B)squared = (B - A)squared

On outskirts of the woods of thought
B saw A bow his head
to mourn the death of one B sought...
and found himself was dead.

A dug one grave for corpse and man.
And turned aside to laugh.
But when B rose to dig, A ran
upon B with the staff,

which B had cut A when it leaved
(though it ran blood, not sap).
There was no combat. They both grieved,
fallen, across the dead man's lap.

[This poem is pretty mysterious, so don't get the idea that I get it 100% and you don't. But what I do get, I love.]