What is a summary of Pope's An Essay on Man: Epistle I?

The first clue to what Pope is getting at in this poem is in the title. An epistle is a letter, and in this poem, Pope is addressing his friend Henry St. John, Lord Bolingbroke. But an "essay on man" is of much larger scope than just a letter between friends. And indeed, what starts as a chummy kind of catching up in the poem soon extends into profound thoughts beyond just these two men, all the way to all of mankind itself. Pope is thinking out loud in the poem and using his friend as a sounding board for his ideas about man's station in the world. Man seems mighty: he has tamed the beasts of burden, he has tilled the fields and made them sprout sustenance, and so he thinks he is above nature. But nature is part of God's system, part of God's laws, and so mankind is just as beholden to the nature of the universe as is the sparrow or the lamb. Indeed, Pope lays out his thesis for the poem in the last line of the first stanza: to "vindicate the ways of God to man." And as the lengthy poem continues, Pope does just that—reminds man that he is beholden to the ways of God. God's divine designs are present in man; man is not above them. To Pope's mind, "The gen'ral order, since the whole began / Is kept in nature, and is kept in man." By the end of the poem, the "truth is clear" to Pope, his friend, and his readers: an essay on man is an essay on the humbling reminder that mankind's power is limited.