The washing called baptism means spiritual washing, which is purification from evils and falsities, and so regeneration.

Acts of washing were enjoined upon the Children of Israel, as is well known from the statutes laid down by Moses. For instance, that Aaron should wash himself before putting on his garments as minister (Lev. 16:4, 24); and before approaching the altar to minister (Exod. 30:18-21; 40:30-32). The same was enjoined upon the Levites (Num. 8:6, 7); and also others who had become unclean through sins, and they were said to be sanctified by acts of washing (Exod. 29:1, 4; 40:12; Lev. 8:6). Therefore the bronze sea and many basins were placed near the temple, so that they could wash themselves (1 Kings 7:23-39). They were instructed to wash the vessels and utensils, such as tables, benches, beds, plates and cups (Lev. 11:32; 14:8, 9; 15:5-12; 17:15, 16; Matt. 23:25, 26).

[2] But the reason why washing and similar acts were ordered and enjoined upon the Children of Israel was that the church established among them was a representative one, and had the character it did so as to prefigure the Christian church which was to come. When therefore the Lord came into the world, He abolished representative acts, all of which were external, and established a church which was in all respects internal. So the Lord banished the symbols and revealed the actual forms, as when someone lifts a curtain or opens a door, allowing what is inside not only to be seen but also approached. Out of all the previous representative acts the Lord retained only two, to contain everything the internal church has in a single pair; these are baptism to replace the acts of washing and the Holy Supper to replace the lamb which was sacrificed every day, and in full measure on the feast of the Passover.