The Verse:
Heroic blank verse as Homer wrote in Greek and Virgil wrote in Latin.

Form:
Like The Iliad and The Aeneid Milton's epic plunges into the narrative at the third crisis, in media res.
(A)Crisis One
The drawing of the rebel angels together and Satan's debate with the seraph, Abdiel.
(B)Crisis Two
The War in Heaven.
(C)Crisis Three
The epic begins here, where Satan and his rebel angels lay vanquished after they have been cast down into Hell.

Theme:
For Milton, God's pupose and power allows him to bring good out of evil. Milton's purpose is "To justify the ways of God to man".
(A)
Man is created because heaven has been depopulated after Satan's banishment from Heaven. Good has come from evil.
(B)
Redemptive hope for humanity is the central message of the epic; this is reflected in the first sentence of the epic. This sentence focuses and encompasses the plot.

"Of man's first disobedience...(evil/spiritual death) to ...Restore us and regain that blissful seat." (good/spiritual life) (ll. 1-5)

Invoking the Muse:
"Sing Heavenly Muse":word placement is used for emphasis. The pause created afterwards creates drama. Milton has a tendency to place important words, often verbs, at the beginning of a line for emphasis. eg.) "Restore us", "Instruct us", "Illumine", "Say first"

Epic Question:
"What cause, favoured of heaven... Who first seduced them to that foul revolt?

Epic Answer:
"The infernal serpent whose guile..."

Satan as a Hero:
In the first two books of Paradise Lost Satan appears a heroic character. He is vast, winged and beautiful. But as the epic progresses, Milton accomplishes the complete degradation of Satan. Finally after his victory in Hell, Satan is completely degraded. He hisses and is forced to slither on his belly like a snake. His spitting angels are tempted by apples, only to have the fruit disintegrate as they taste them. They are left alone to suffer in Pandamonium.
Satan's problem, and Milton's definition of sin, is that he is desired not only to exalt himself by battling God, but to exalt himself by "reigning equal over equals". This action separates him from the rest of creation and from God. It causes spiritual death and conflict.
Innocence and bliss by contrast come from being content with one's place in creation and from striving for the greater good of all creation. To be united with creation and with God means spiritual life.