Unclean! Unclean!

A man who has lost his hair and is bald is clean. If he has lost his hair from the front of his scalp and has a bald forehead, he is clean. But if he has a reddish-white sore on his bald head or forehead, it is a defiling disease breaking out on his head or forehead. The priest is to examine him, and if the swollen sore on his head or forehead is reddish-white like a defiling skin disease, the man is diseased and is unclean. The priest shall pronounce him unclean because of the sore on his head. Anyone with such a defiling disease must wear torn clothes, let their hair be unkempt, cover the lower part of their face and cry out, “Unclean! Unclean!” As long as they have the disease they remain unclean. They must live alone; they must live outside the camp.

—Leviticus 13:40–46


Leviticus, the third book of the Hebrew Pentateuch and of the Christian Old Testament, consists primarily of a recitation of religious laws and codes. Its name refers to the tribe of Levi, from whose ranks the priestly class came, and along with a series of injunctions regarding the proper modes of ritual worship—types of animals suitable for various sacrificial offerings, ceremonial protocols, and the like—it also includes a significant interlude on the ecclesiastical detection and quarantine of physicalized forms of impurity. 


The thirteenth and fourteenth books of Leviticus are concerned particularly with “surface afflictions.”^[1] Both address forms of domestic impurity—fabrics, for instance, that are moldy or mildewed; walls of houses disfigured “with greenish or reddish depressions”—but the thirteenth takes as its central subject skin diseases. Thought to be a punishment from God, cutaneous disorders were legible signs of divine disfavor, unholy and suggestive of death. The conditions referred to in Leviticus and elsewhere throughout both the Old and New Testament have traditionally been gathered together in translation under the catchall term “leprosy.”^[2] This text’s epigraph, however, taken from the New International Version of the Bible, reflects the current scholarly uncertainty about the precise nature of the skin ailments referenced in these and other passages.^[3] As leprosy was not attested in the Near East when Leviticus was compiled in the sixth century BC, the original Hebrew term tsar ‘at is now understood to refer not to Hansen’s disease, as leprosy is today known, but to a range of skin diseases including eczema, impetigo, and especially, given the nature of descriptions like the one above, psoriasis.^[4] Thus in many modern-day translations of the Bible, the word is often replaced—not by what would be the anachronistic name of one of these diseases, but by a more generalized descriptor such as “malignant,” “virulent,” or, as above, “defiling.”