In most so-called confessional poetry, there is no governing vision of submergence or transcendence as there is in Wordsworth. Submergence occurs when the poet uses darkness as a medium and communicates with his own unconscious. It is through such process that the poet makes the universe internal until it takes on his form. Transcendence is the process by which the poet puts himself into the universe until he becomes identified, with the divine event. Light is its medium. In confessional poetry, the self is terminal, physical, isolated.....This one is a weighty essay but I enjoyed the book very much especially A Poet's Alphabet, On Becoming a Poet, the Introduction to The Best American Poetry 1991, Notes on the Craft of Poetry, and an interesting essay about the appearance of Parnassus in 4 different poems by US poets.
 You can read this and other essays by Mark Strand in his book: The Weather of Words. Also, read this article about the book by Edward Bryne.