When you want something to be memorable, you repeat it. In literature, repetition refers specifically to the recurrence of words, sounds, or phrases. The reason for using repetition, other than hammering home a particular idea or instruction, is to increase the sense of unity in a work.
The Puritan preacher Jonathan Edwards (1703-1758) relies heavily on the use of repetition in order to impress upon his audience the urgency of redemption from sin. Two of the most prominent uses of repetition within the sermon are the words “wrath” and “restrain(s)/restraint.”
Edwards uses the word “wrath” an astonishing fifty-one times. God, he warns, will not be patient with his errant flock forever. Every day his anger at humanity’s sin and indifference towards their own fate increases. Here are just a few examples of the use of “wrath” in the text:
On Eternal Damnation: “The wrath of God burns against them, their damnation does not slumber; the pit is prepared, the fire is made ready, the furnace is now hot, ready to receive them; the flames do now rage and glow.”
On the Foolishness of Waiting for Last-Minute Deathbed Conversions: “Death outwitted me: God's wrath was too quick for me. Oh, my cursed foolishness!”
On God’s Waning Patience: “The wrath of God is like great waters that are dammed for the present; they increase more and more, and rise higher and higher, till an outlet is given; and the longer the stream is stopped, the more rapid and mighty is its course, when once it is let loose.”
Another word employed time and again is “restrain.” God’s mercy, Edwards cautions, is almost at its end. Over and over, the audience hears that divine restraint is the sole reason why sinners do not yet burn:
By the mere pleasure of God, I mean his sovereign pleasure, his arbitrary will, restrained by no obligation, hindered by no manner of difficulty, any more than if nothing else but God's mere will had in the least degree, or in any respect whatsoever, any hand in the preservation of wicked men one moment.
In this instance of “restraint,” Edwards speaks to the authority of God over demons. God alone “restrains” them from devouring sinners:
God restrains their wickedness by his mighty power, as he does the raging waves of the troubled sea, saying, "Hitherto shalt thou come, but no further;" but if God should withdraw that restraining power, it would soon carry all before it.
The other literary device that makes Edwards's sermon unforgettable is his use of colorful imagery to illuminate the horrors that await the sinner who dies without redemption:
On Humanity’s Inability to Escape Punishment: "Your wickedness makes you as it were heavy as lead, and to tend downwards with great weight and pressure towards hell; and if God should let you go, you would immediately sink and swiftly descend and plunge into the bottomless gulf, and your healthy constitution, and your own care and prudence, and best contrivance, and all your righteousness, would have no more influence to uphold you and keep you out of hell, than a spider's web would have to stop a falling rock."
On the Reality of Hell: "O sinner! Consider the fearful danger you are in: it is a great furnace of wrath, a wide and bottomless pit, full of the fire of wrath, that you are held over in the hand of that God, whose wrath is provoked and incensed as much against you, as against many of the damned in hell."
On Dying Unrepented: "But when once the day of mercy is past, your most lamentable and dolorous cries and shrieks will be in vain; you will be wholly lost and thrown away of God, as to any regard to your welfare."
There is a unity of effect Edwards creates through his use of repetition and terrifying images: to impress upon his audience the gravity of their sin, the growing impatience of God, and the urgency of repentance.