Final answer:
Milton's purpose in writing 'Paradise Lost' is revealed in the lines that express his intent to assert divine providence and justify the ways of God to humanity, highlighting the poem's theological objectives.
Step-by-step explanation:
The two lines from John Milton's Paradise Lost that provide clues to his purpose in writing the epic poem are: "That to the highth of this great Argument / I may assert th' Eternal Providence, And justifie the wayes of God to men." These lines clearly indicate Milton's intention to explain and vindicate the actions and intentions of divine providence, particularly how it relates to humanity's fall and ultimate redemption. By declaring his aim to 'justify the ways of God to men,' Milton sets forth the epic's theological and philosophical groundwork, affirming the work's serious and didactic nature.