There are natural tools and processes for the removal of impurities from natural elements like silver and gold. But man’s heart is so hidden, so deceptive, and his thought and motives are so tangled with sin, that there are no natural ways to purify his heart and mind of sin. Secular psychology may attempt to achieve this, but will not succeed. Only Christ, whose eyes are like a flame of piercing and purging fire (Revelation 1:14), can penetrate and purify our hearts. How grateful we should be when He does so.
3 The crucible is for silver, and the furnace is for gold, and the LORD tests hearts.