How does some of the power of Edward's sermon derive from his use of parallel constructions?
In his fire and brimstone speech, Jonathan Edwards makes effective use of parallel constructions in order to create images and elicit emotions that will generate an understanding in his congregation of the precariousness of their situation on earth.
The repetition of a grammatical structure, parallelism is an effective rhetorical device used to link together related ideas, and thereby provide clarity and emphasis. For example, Edwards inspires fear as he stresses how the sinners hang over the flames of hell "by a slender thread" of God's goodness with nothing else to hold them:
You hang by a slender, with...nothing to lay hold of to save yourself, nothing to keep off the flames of wrath, nothing of your own, nothing that you ever have done, nothing that you can do, to induce God to spare you one moment....
This repetition of the word nothing inspires fear as stress is placed upon man's complete inability to save himself.
Another earlier use of parallelism that also inspires fear is the metaphor of God's bow and the repetition of the image of the arrow of wrath. Edwards tells his congregation that God's justice bends the arrow and strains the bow, but it is the "mere pleasure of God" that prevents the arrow from striking them.