This poem is probably one of Wordsworth's only nationalistic poems. He seems frustrated with the way English society has fallen away from the noble virtues of just a few years ago.
He begins the poem with an exclammation and a dramatic outcry.
Milton! England has need of you.
Wordsworth feels that Milton exemplified all that was good about English society. Milton wrote Paradise Lost some time back and was considered a moral and virtuous poet. Milton's soul is as bright as a star, he stood alone above the crowd. etc.
Wordsworth was concerned with ethical morality and the natural sense of morality his poems might communicate to his readers. Wordsworth was not a sensualist as some might imagine. He sees England as a quagmire or swamp full of selfish men. We wishes Milton were here to teach "manners, virtue, freedom, power."