Books XI and XII change the focus of Paradise Lost. The plot of Adam's and Eve's fall has been completed. The final scenes for most characters have occurred. A brief conclusion seems logical. Instead, Milton adds two more books that trace biblical history through Jesus. Many scholars and readers have questioned the artistic justification for these books, and, in truth, the books do seem to needlessly prolong the work. On the other hand, several solid arguments can be adduced to explain the reasons for Books XI and XII, if not their necessity.
Milton's stated purpose in the poem is to justify God's ways to Man. By the end of Book X, Milton has been able to explain his concept of what God did and why, but he has offered little in the way of justification. Can the single instance of disobedience by Eve and then Adam justify death, war, plague, famine — an endless list of evil? To truly accomplish his goal, Milton needs to show the effects of the fall on Adam and Eve over a longer period and at the same time develop the notion that some greater good than innocence and immortality in Paradise could result from the fall. Books XI and XII represent Milton's attempt at justification.
