Probably the most famous quote about Paradise Lost is William Blake's statement that Milton was "of the Devil's party without knowing it." While Blake may have meant something other than what is generally understood from this quotation (see "Milton's Style" in the Critical Essays), the idea that Satan is the hero, or at least a type of hero, in Paradise Lost is widespread. However, the progression, or, more precisely, regression, of Satan's character from Book I through Book X gives a much different and much clearer picture of Milton's attitude toward Satan.
Writers and critics of the Romantic era advanced the notion that Satan was a Promethean hero, pitting himself against an unjust God. Most of these writers based their ideas on the picture of Satan in the first two books of Paradise Lost. In those books, Satan rises off the lake of fire and delivers his heroic speech still challenging God. Satan tells the other rebels that they can make "a Heav'n of Hell, a Hell of Heav'n" (I, 255) and adds, "Better to reign in Hell than serve in Heav'n" (I, 263). Satan also calls for and leads the grand council. Finally, he goes forth on his own to cross Chaos and find Earth. Without question, this picture of Satan makes him heroic in his initial introduction to the reader.
Besides his actions, Satan also appears heroic because the first two books focus on Hell and the fallen angels. The reader's introduction to the poem is through Satan's point of view. Milton, by beginning in medias res gives Satan the first scene in the poem, a fact that makes Satan the first empathetic character. Also, Milton's writing in these books, and his characterization of Satan, make the archfiend understandable and unforgettable.
These facts certainly make Satan the most interesting character in the poem — but they do not make him the hero. Because the reader hears Satan's version first, the reader is unaware of the exaggerations and outright lies that are parts of Satan's magnificent speeches. Moreover, the reader can easily overlook the fact that Milton states that, whatever powers and abilities the fallen angels have in Hell, those powers and abilities come from God, who could at any moment take them away.
In essence then, Milton's grand poetic style sets Satan up as heroic in Books I and II. The presentation of Satan makes him seem greater than he actually is and initially draws the reader to Satan's viewpoint. Further, because all of the other characters in the poem — Adam, Eve, God, the Son, the angels — are essentially types rather than characters, Milton spends more artistic energy on the development of Satan so that throughout the poem, Satan's character maintains the reader's interest and, perhaps, sympathy — at least to an extent.
No matter how brilliantly Milton created the character of Satan, the chief demon cannot be the hero of the poem. For Milton, Satan is the enemy who chooses to commit an act that goes against the basic laws of God, that challenges the very nature of the universe. Satan attempts to destroy the hierarchy of Heaven through his rebellion. Satan commits this act not because of the tyranny of God but because he wants what he wants rather than what God wants. Satan is an egoist. His interests always turn on his personal desires. Unlike Adam, who discusses a multiplicity of subjects with Raphael, rarely mentioning his own desires, Satan sees everything in terms of what will happen to him. A true Promethean / Romantic hero has to rebel against an unjust tyranny in an attempt to right a wrong or help someone less fortunate. If Satan had been Prometheus, he would have stolen fire to warm himself, not to help Mankind.
Milton shows his own attitude toward Satan in the way the character degenerates or is degraded in the progression of the poem. Satan is magnificent, even admirable in Books I and II. By book IV, he is changed. In his soliloquy that starts Book IV, Satan declares that Hell is wherever he himself is. Away form his followers and allowed some introspection, Satan already reveals a more conflicted character.
Similarly, Satan's motives change as the story advances. At first, Satan wishes to continue the fight for freedom from God. Later his motive for continuing the fight becomes glory and renown. Next, the temptation of Adam and Eve is simply a way to disrupt God's plans. And, at the end, Satan seems to say that he has acted as he has to impress the other demons in Hell. This regression of motives shows quite a fall.
Satan also regresses or degenerates physically. Satan shifts shapes throughout the poem. These changes visually represent the degeneration of his character. First, he takes the form of a lesser angel, a cherub, when he speaks to Uriel. Next, he is a ravening cormorant in the tree of life — an animal but able to fly. Then he is a lion and a tiger — earth-bound beasts of prey, but magnificent. Finally, he is a toad and a snake. He becomes reptilian and disgusting. These shape changes graphically reveal how Satan's actions change him.
Even in his own shape, Satan degenerates. When Gabriel confronts Satan in Book V, none of the angels initially recognize Satan because his appearance is noticeably changed. Likewise, in Book X, when Satan once again sits on his throne in Hell, none of the earlier magnificence of his physical appearance is left. Now he looks like a drunken debauchee.
Though Satan is not heroic in Paradise Lost, he at times does border on tragedy. Ironically, he also borders on comedy. The comic element associated with Satan derives from the absurdity of his position. As a rebel, he challenges an omnipotent foe, God, with power that is granted him by his foe. God simply toys with Satan in battle. Satan is, in fact, cartoonish when he and Belial gloat over the success of their infernal cannon in Book VI. Satan and Belial stand laughing at the disorder they have caused, but they are unaware of the mountains and boulders just about to land on their heads.
If all of Paradise Lost were on the level of the battle scene, the poem would be comic. But Satan's temptation of Adam and Eve moves the demon closer to tragedy. Satan's motives in destroying the human couple may be arguable, but the effect and its implications are not. Satan brings the humans down and causes their removal from Eden. In so doing, he also provides the way to salvation for those humans who choose freely to obey God. However, Satan provides nothing for himself. Hell is where Satan is because he has no way to rejoin God. Unlike humanity, Satan and the other fallen angels have already sealed their fates. They live always with the knowledge of Hell.
In the end, Satan calls to mind the Macbeth of Shakespeare. Both characters are magnificent creations of evil. Both are heroic after a fashion, but both are doomed. Both are fatalistic about the afterlife. Satan knows that he must remain in Hell; Macbeth says that he would "jump the life to come," if he could kill Duncan with no consequence on Earth. Both characters are the driving force in their own works. And finally both create a kind of Hell; Macbeth's on Earth, Satan's in the universe.