A harrow is “an instrument of agriculture, formed of pieces of timber sometimes crossing each other, and set with iron teeth.” It is the process of drawing the instrument “over plowed land to level it and break the clods, and to cover seed when sown.” Mormon seems to be using the word as both the instrument and the process. He did not wish “to tear; to lacerate; to torment” the tender souls of his readers with the horrors of his day (Webster, American Dictionary).