It’s been a lovely meal, from the fresh-baked French bread to the sinful chocolate mousse — every bite. All that is left to do is to recite Grace After Meals (Birkat Hamazon) thanking God for the food. But would you be surprised to learn that there is an additional religious rite to perform before the concluding Grace?

Just as the hands are washed before a meal (in which one eats bread), before the conclusion of the meal there is a special hand washing ritual known as mayim acharonim (literally: “final waters”).

Mayim acharonim is usually done at the table with a small cup of water and a small bowl into which to spill the used water. There is no blessing, and the “dirty” water should either be covered or removed from the table before Birkat Hamazon. Customs for mayim acharonim vary. Some only do it when there are three or more people present, some only when there are 10 or more, and others every time one eats bread. Likewise, how much of the hand or fingers are washed varies according to custom.

Some sages have disputed the necessity of maintaining this practice because it stems from the need to wash off “Sodomite salt.” This pungent salt was sometimes mixed into table salt in Talmudic times and could potentially cause blindness if rubbed in the eye. Since this salt is no longer in use, the mayim acharonim might appear to be unnecessary.

Washing one’s hands as part of Jewish ritual, however, is not about cleanliness of the body (although that is an added bonus), but cleanliness of the soul. As one is about to thank the Creator for all that has been provided, washing one’s hands reminds a person to separate from the physical and to focus on the spiritual.