from Richard Hugo, Triggering Town
a poem has two subjects: a triggering subject that gets it going and a generated subject that the poem discovers along the way. The first subject is finally just a way of accessing the poem’s true subject. The first subject is the map, the second the treasure.
Billy Collins adds: “In a poem of recollection, the trouble often is that the memory itself can exert so strong a grip on the poet that the poem never leaves the confines of the past, never achieves the kind of escape velocity that would propel it to another, more capacious dimension. [These are] poems that are primarily driven by the engines of memory rather than the engines of imagination.”
(when I first read this, I thought he had written “capricious dimension,” an idea I find much more intriguing that “capacious.”)
from After Confession: Poetry as Autobiography