The epic poem Paradise Lost by John Milton tells of the casting out of paradise of Satan and other rebellious angels. Satan and his demons devise a plan to retaliate against God by corrupting his new creation—Man. Since Adam and Eve have been given free will, God allows Satan to approach and tempt them. Adam and Eve disobey God and fall from grace, and God sends the archangel Michael to drive them out of the Garden of Eden.
In the prologue to book 1, Milton delineates two main themes of Paradise Lost. In line 1, he announces that he will write "of man's first disobedience." That obedience to God is an absolute requirement of all creation is emphasized throughout the poem. The expulsion of Satan and his minions from heaven is an example of the consequences of disobedience and rebellion. Similarly, the punishment of Adam and Eve for their disobedience is expulsion from the Garden of Eden.
The hierarchy of God's authority over his creation must be observed at all times, and to disregard God's supremacy has drastic ramifications. Furthermore, as Milton explains, Adam and Eve's transgression brings "death into the world and all our woe." Note that the use of the word "our" makes it clear that man's first disobedience condemns the entire human race to death and expulsion from the heavenly garden.
Milton proclaims the other main theme of the poem in lines 24 to 26: "That to the height of this great argument I may assert Eternal Providence and justify the ways of God to men." According to the Merriam-Webster Dictionary, providence means "divine guidance and care," or, "God conceived as the power sustaining and guiding human destiny." To justify something is "to prove or show to be just, right, or reasonable."
In other words, Milton's intention is not only to tell of man's disobedience and fall but also to prove that God's actions as a result are just, right, and reasonable considering the circumstances. It is important to remember that in books 11 and 12 of Paradise Lost, before he sends Adam and Eve out of the garden, Michael gives them an overview of Biblical history, including an account of the Messiah and his ultimate victory over death.