BOOK II presents the "great consult": Moloch urges open war against Heaven, while Belial counsels complete passivity lest worse befall them, and Mammon proposes exploiting the riches of Hell; Beelzebub offers what purports to be a compromise, but is really the plan predetermined by Satan, namely, an attack, by guile, not force, against God through his latest creation, man. Satan now intervenes to announce that he will undertake the perilous journey to earth to spy out the land. In his absence his followers explore their new domain, which enables the poet to complete his description of Hell. Meanwhile Satan reaches the gate of Hell and finds it guarded by his daughter, Sin, and his son by her, Death; and the book concludes with his journey through the realms of the anarch Chaos to the outer sphere of the earthly universe.
BOOK III commences with the famous invocation to light, and, leaving Satan, introduces us to Heaven, where, in the presence of the Angels, the Father explains that, of his own free will, and subject to no compulsion, man will succumb to Satan's wiles, and the Son offers, in this event, to suffer the inevitable punishment in man's stead. (The first is essential to the declaring of God's justice; the second to the assertion of eternal Providence.) The remainder of the book narrates Satan's descent through the spheres, past Uriel, the guardian of the sun, whom he deceives, down to earth.