The Pilgrim: A Hammer Beyond Thor

The instrument with which the heart is broken, and with which the spirit is made contrite, is the Word. …This rock, this adamant, this stony heart, is broken and made contrite by the Word. But it only is so, when the Word is as a fire, and as a hammer to break and melt it. And then, and then only, it is as a fire, and a hammer to the heart to break it, when it is managed by the arm of God. No man can break the heart with the Word; no angel can break the heart with the Word; that is, if God forbears to second it by mighty power from heaven. …Wherefore, though the Word is the instrument with which the heart is broken, yet it is not broken with the Word, till that Word is managed by the might and power of God. —John Bunyan, The Acceptable Sacrifice