Soap

Soap in the ancient biblical world was not the fatty-acid soap of modern chemistry but a vegetable alkali — a cleaning agent made from the ashes of certain plants rich in potash or sodium carbonate. The Hebrew borith (from a root meaning to be clean) is the term used in Jeremiah 2:22 and Malachi 3:2. Jeremiah 2:22 uses it in a devastating metaphor: Though you wash yourself with lye and use much soap, the stain of your guilt is still before me. No amount of ritual or moral cleansing can remove the corruption of Israel's idolatry. Malachi 3:2 asks who can endure the day of the coming messenger: he is like a refiner's fire and like fullers' soap — the soap used by those who cleaned and whitened cloth. The image is of purifying divine judgment that will both cleanse the Levites and expose the guilt of the wicked.