The lines that provide clues to John Milton's purpose in writing the Paradise Lost poem are:
say first what cause
Mov'd our Grand Parents in that happy State
Explanation:
This poem is based on Genesis, the first book of the Bible. These two lines of the poem have the purpose of showing the reason why Adam and Eve were expelled from paradise. When Milton used the expression "our Grand Parents" he was referring to Adam and Eve and when he used "what cause" he was referring to the reason for the expulsion. Thus, these phrases show the purpose of the poem, which was to explain the origin of satan and to show the reason that made Adam and Eve expelled from paradise.
