Last week’s Parshah described the signs of the metzora (commonly mistranslated as “leper”)—a person afflicted by a spiritual malady which places him or her in a state of ritual impurity. This week’s Torah reading begins by detailing how the recovered metzora is purified by the kohen (priest) with a special procedure involving two birds, spring water in an earthen vessel, a piece of cedar wood, a scarlet thread and a bundle of hyssop.

A home can also be afflicted with tzaraat by the appearance of dark red or green patches on its walls. In a process lasting as long as nineteen days, a kohen determines if the house can be purified, or whether it must be demolished.

Ritual impurity is also engendered through a seminal or other discharge in a man, and menstruation or other discharge of blood in a woman, necessitating purification through immersion in a mikvah.