Book I of Paradise Lost begins with Milton describing what he intends to undertake with his epic: the story of Man's first disobedience and the "loss of Eden," subjects which have been "unattempted yet in prose or rhyme." His main objective, however, is to "justify the ways of God to men."
The poem then shifts to focus on the character of Satan who has just fallen from heaven. The scene opens in a fiery, yet dark, lake of hell. Satan, dazed, seems to be coming to consciousness after his fall and finds himself chained to the l lifts his head to see his second in command, Beelzebub, the Lord of the Flies, who has been transformed from a beautiful archangel into a horrid fallen angel. Satan gets his bearings and, in a speech to Beelzebub, realizes what has just happened: Satan, presuming that he was equal to God, had declared war on the creator. Many angels had joined Satan, and the cosmic battle had shaken God's throne.
Satan and his cohorts had lost and been cast "nine times the space that measures day and night" to hell. Still, Satan tells Beelzebub that all is not lost. He will never bow down to God and now, knowing more of the extent of God's might, the rebel angels might better know how to continue to fight him in an eternal war.
Beelzebub questions why they themselves still exist. What plan did God have for them since he did not kill them completely, but left them their souls and spirits intact to feel pain in hell?
Satan replies that God indeed wanted to punish them by forcing them to languish in hell for eternity. But, he says, that means that they don't ever have to obey God again. In fact, Satan says, they must work to instill evil in all good things so as to always anger God.
Satan and Beelzebub gather their strength and fly off the fiery lake to firmer, though still fiery, ground. They look around at the dark wasteland that is hell, but Satan remains proud. "Better to reign in hell, then serve in heaven."
They see their army lying confused and vanquished in the fiery lake. Satan calls to them and they respond immediately. Satan gathers his closest twelve around him .
Music plays and banners fly as the army of rebel angels comes to attention, tormented and defeated but faithful to their general
They could not have known the extent of God's might, Satan tells them, but now they do know and can now examine how best to beat him. Satan has heard of a new kind of creation that God intends on making, called man. They will continue the war against heaven, but the battlefield will be within the world of mankind.
The army bangs their shields with their swords in loud agreement. The rebel angels then construct a Temple, a throne room, for their general and for their government, greater in grandeur than the pyramids or the Tower of Babylon.
All the millions of rebel angels then gather in the Temple for a great council, shrinking themselves and become dwarves in order to fit.