Hastings' Dictionary of the Bible (1898)
PURIFICA'TIONS formed a very conspicuous feature among the ritual observances of the Jews, and were performed in various ways, though generally by means of water. Besides their spiritual meaning, referring to the purity of the heart, they had often also a sanitary purpose. After the Captivity, however, they were carried into extremes, especially by the Pharisees. Mark 7:3-4.