The epic nature of Paradise Lost is justified by the exactitude with which it adheres to the epic conventions. In brief the epic conventions are “ Statement of the theme of the epic in the first few lines, Starting in medias res ( in the middle of things), Invocation of the muse, Grand style, and epic similes.
Paradise Lost fulfills all these characteristics in the seriousness of the tone, the elevated theme, and excellence in expression as it narrates the story
“Of man’s first disobedience
and the fruit of the forbidden tree
whose mortal taste brought death into the world”
Milton invokes the aid of the muse in this stupendous task,
“Invoke thy aid to my adventurous song
That with no middle flight intends to soar
Above the Aonian mount, while it pursues
Things unattempted yet in prose or rhyme.”
EMW Tillyard says an epic is defined by its comprehensiveness, being inclusive in its structure with room for a great variety; the tragic, the instructive, the lyrical, the dramatic, the comic and the domestic emotions.Paradise Lost according to him has a structural unity, a strong sense of the whole, a sense of the overall design. Possessing a choric quality according to Tillyard, Paradise Lost speaks not only for its author, but through him to a large body of people. As an epic it expresses the spirit of an age or of a Nation, or of a religion and not merely the feelings and ideas of an individual.
Deeply religious, the poem speaks about the unflinching spirit of an individual who wrote “ They also serve those who stand and wait”