I'd like to try to understand the various transitions and structure of the poem. Here's sort of how I summarize the various sections, and I'll refer to Petrarch's sub-divisions.
Sub-Division 1: The need to sing of his death.
Sub-Division 2:
(a) The change now that he's gone.
(b) What could we have done to prevent it.
(c) He died attempting to acquire fame.
(d) How he died.
Sub-Division 3: Shepherd's work.
Sub-Division 4:
(a) Look homeward, to Paradise
(b) Weep no more.
There may be more that I've glossed over. First there is a sort of classical logic to it. Does anyone know if this is a classical/medevil/renaissance rhetorical form? It's interesting Milton delays how King died well into the poem. Perhaps it was a well known fact.
The section I found the most interesting was the sub-division 3, the shepherd's work. The other sections, despite Milton's great voice, seem kind of sterile, almost like a fossil. There's just way too much classical allusions and given that he's working with a fixed established form (I guessing), it gives the feel of a petrified piece of wood. Sub-division 3 doesn't feel that way to me. It seems like he lets his imagination run there, and, even though the whole shepherd's thing is kind of corny, it's not bogged down with learned name droppings.