Writing Paradise Lost in the wake of the Restoration, Milton the Puritan was really in dire straits. Having been an outspoken advocate of the regicide during the Commonwealth as Latin Secretary, a key figure in Cromwell's propaganda team, he was only spared execution because of the intervention of powerful friends, among them the poet Andrew Marvell, and also his blindness was considered punishment enough. For Milton, then, to write such a daring, innovative, and provocative masterpiece, a scathing satire which is at times heretical, truly attests to the courage of this great spirit. If he had not been spared we would have been denied arguably the greatest poem written in English.
The poem operates on so many levels, all of them subtly ambiguous. Milton deftly plays with the classical epic form to produce a Christian epic depicting the Fall of Man that demonstrates his profound erudition. He combines the best of Christian philosophy with his own controversial religious views in order to "justify the ways of God to men" in a comprehensive spiritual worldview. However, religion is not the only subject here. Paradise Lost is also a skilful satire on the politics of the Revolution and Milton's experience of defeat. There is even a history of the future in which the Archangel Michael describes to Adam the fate of his descendants, how the first tyrant, Nimrod, arose, and how Christ will deliver salvation. It also displays the Renaissance man's understanding of the cumulative knowledge of society, for example, the poem subscribes to neither the classical natural philosophy of the Ptolemaic system or the new rational scientific understanding of Copernicus. He even suggests the possibility that aliens exist! It is also extremely incisive in terms of psychology: "The mind is its own place, and in itself / Can make a Heav'n of Hell, a Hell of Heav'n".
The language is heavily latinate, with long sentences containing multiple clauses, and incorporates many new latinate and Greek words into English, often for the first time. The poetry nevertheless is very rythmical and the verve is exceptional. It is divine poetry, maybe even divinely inspired, as Milton's nephew John Phillips described how Milton would wake up in the morning with verses already composed in his head. At all times Milton observes what he saw as the principle of all good poetry - decorum, the appropriateness of the language for the subject, which in this case is as high as it gets. And refreshingly for a Renaissance poem of this length, Paradise Lost does not rely in the slightest on conceits or conventions.
Possibly the best thing about the narrative itself is the character of Satan, who really is the main protagonist. From the time he rises from the Lake of Fire till his Pyrrhic victory over mankind, his pride and pathos make him admirable and hard to hate outright. His remorse, longing, and ultimate resolution to rebel is described with such breathtaking virtuosity of rhetoric it makes him one of the great inventions of literature. Indeed, so sympathetic was Milton's portrayal of Satan, he is the most human character in the poem, which led Blake to wryly comment that Milton was of Satan's party without knowing it - but that this was the reason he was a great poet. Milton's magnanimity is able to view all sides of an argument, but ultimately he makes his own decision about what is right and sticks by his guns till the death.