Thomas Greene on Shakespeare's sonnets:
"Thus we are left with two distinct sources of alleged value, the friend and the poetry, each the basis of a rudimentary economic system, each vulnerable to skepticism. The presence of each system tends to destabilize the other by casting doubt on the kind of value it attempts to establish. To cite the poetic convention behind each system does not adequately deal with its constituent presence in this work."
I think this is right. I might go a step further, too. In the young man portion of the sequence, there are really three arguments that inflect each other: the procreation sonnets which worry that Time will deface the young man's beauty; the Ovidian argument that poetry will outlast Time; and the rival poet sonnets, in which the physical fact of the young man prevents the poet from writing poetry. I'm oversimplifying quite a bit, in reducing this aspect to a sort of Shakespearean Paper-Rock-Scissors, but I do think the tropes of fullness and emptiness (or content and form) that Greene and others point out are affiliated at different times with ostensibly contradictory pieces of these arguments. Time, the youth, and poetic style are all alternately 'empty' and 'full' with regards to each other.
(Empty wins.)
