The other day I came across an interview with one of my favorite poets, A.E. Stallings, in which she says:
Rhyme is not an “ornament”-it is essential to a rhyming poem; without it, the poem would not have happened. That is, the poet does not “know” exactly what the poem is going to say and “translate” it into rhyming verse-or shouldn’t, in my book. On the contrary, it is the strange dream-logic connections of the rhymes themselves that lead the poem forward, perhaps into territory the poet herself had not intuited. Rhyme is a method of composition.
I just love this, and it perfectly articulates the experience I have when I'm composing a sonnet--and why I so love writing in that form.
The full interview is here:
http://www.valpo.edu/vpr/v12n1/v12n1prose/stallingsinterview.php