Paradise Lost, considered by many to be Milton’s masterpiece, is one of the most ambitious poems ever written. It is an epic poem written in blank verse. Milton follows Virgil's epic construction closely. As the Greeks and Romans began their epics asking for the inspiration of the muses, similarly Milton declares that he cannot fulfill his task without the help of the Holy Spirit. Built on a vast range of biblical and classical scholarship, Paradise Lost attempts to tell the story of the Fall of Adam and Eve in 12 cantos or books. The central argument of the poem is a question: Was the Fall of Man in the Garden of Eden caused by Eve eating the apple from the tree of knowledge, or was it an act of free will and primal disobedience? .
The poem is divided in twelve cantos, each of which is preceded by a summary of its argument. Milton conceived his poem according to a complex mathematical structure whose parts were interrelated in a precisely way, according to principles derived from the Hebrew Cabala and the Jewish tradition of mystical interpretation of the scriptures. Milton's universe is based on the Ptolemaic model of an ordered hierarchy stretching from the highest being, God, to the lowest, the beasts of the field.
Some critics say that Milton's work is a political allegory of the English history of a period. The rebellion of the angel Lucifer seems to refer to the rebellion of the Puritans against King Charles I which led to the English Civil War and the establishment of the Commonwealth.
One of the most problematic features of Paradise Lost is its language, which is highly ornate and often obscure, in fact, itself is one of the key themes of the poem. Milton makes use of Latin constructions and Latin derived-vocabulary, as well as numerous classical and Biblical allusions. Language before the fall was innocent and was connected to morality, the act of speaking. It is the angel Lucifer, thrown out of heaven for refusing God's word, whose name is changed to Satan and who thus becomes the first to manipulate language, to question its meaning.