Leviticus 13:2

If a man have in the skin of his flesh a rising tumour or a white spot, and it be in the skin of his flesh (as) the plague of leprosy, let him be brought unto Aharon the priest, or to one of the priests his sons.

Someone [Hebrew: ’adam] Scripture did not use the other term for “man” — ’ish (which denotes anyone of the House of Israel) — in order to include the foreigners. Compare, “any man among you who brings a sacrifice” [1:2]. In sacrifices there is one law for natives and aliens alike. Scripture also includes the foreigner in order that he should not render others ritually impure, since ṣara‘at is a contagious disease.

let him be brought willingly or unwillingly. Whoever notices any one of these symptoms may compel him to appear.

Aaron denotes the High Priest, who will replace him one of his descendants denotes one of the ordinary kohanim, who can be found outside of the Temple, like the kohanim of ⊂ Anatot [Jeremiah 1:1].

the kohanim excludes those who are unfit to serve

a s̀’et a kind of burn (compare: “beacon” [Judges 20:40]; “David burned them” [II Samuel 5:21]), whose derivation from the root to lift probably owes itself to the nature of fire, which is to be lifted upward.

a sappaḥat from the words “reposit me” [I Samuel 2:36] and “they shall attach themselves” [Isaiah 14:1] — a disorder that converges on one place

a baheret from “bright light” [Job 37:21]. This is known to be a telltale symptom.

SE’EITH O SAPACHATH O BAHERETH’ (A RISING, OR A SCAB, OR A BRIGHT SPOT). “These are the names of the plagues, each one whiter than the other.” This is Rashi’s language. Rabbi Abraham ibn Ezra wrote that “se’eith is a term for ‘burning,’ the word being associated with the expressions: ‘v’hamaseith’ (and the beacon) began to arise up; ‘va’yisa’eim’ (and) David (burned them). It is possible that it is called se’eith [literally: ‘uprising,’ ‘swelling’], because it is in the nature of fire to rise upwards. Sapachath is of the root: ‘sphacheini’ (attach me), I pray; ‘v’nispechu’ (and they shall cleave) to the house of Jacob — signifying a sickness which attaches to one place. Bahereth is of the root, ‘bahir’ (bright) in the skies, becoming a sort of sign or mark.” [Thus far is Ibn Ezra’s interpretation.] If so, the term se’eith is the name of the plague caused by the bitter green burning fluid [in the body], Note 264. and bahereth is caused by the white fluid, and sapachath is brought about by a combination of both of these fluids. Now our Rabbis have said: “The word se’eith is always an expression of ‘rising,’ and so it is stated in Scripture, And upon all the high mountains, and upon all the hills ‘hanisa’oth’ (that are lifted up), and sapachath always means ‘attachment,’ and se’eith. To each of these two colors Scripture has added a sapachath — a second shade of it. Thus the number of colors is four. See further, Notes 105 and 107, for the precise nature of these colors and their gradations. and so it is stated in Scripture, ‘sphacheini’ (attach me), I pray.”

אדם כי יהיה בעור בשרו, none of the verse in the chapters following may be interpreted in the way he sound when read superficially as the phenomena described do not correspond to any skin diseases we are familiar with, and are not subject to medical treatment. What applies to the human skin applies in the same degree to stains on clothing which are described her as well as to manifestations of “mildew” or something similar breaking forth from the walls of houses. The only criteria which we can apply to what is spelled out in these chapters 12-15 are those laid down by our sages of the Midrash, the Talmud, etc, all of which date back to the instructions received orally from Moses.

כי יהיה בעור בשרו, according to tradition, a reference to a skin irregularity on the skin of (surrounding) the beard or the head. Compare verse 29. The Torah had to use the expression

שאת to describe an elevation of the skin in the area afflicted. This is not an actual elevation but an optical impression, i.e. it is not as white as for instance בהרת. We know that בהרת represents the highest purest degree of the colour “white.” This is clear from Job 37,21 בהיר הוא בשחקים, ”although it is brilliantly bright in the sky.” This colour described as שאת is somewhat עמוקה, “deeper,” in the sense of “a lower degree of” בהרת the most brilliant kind of white.

ספחת, a word which is subordinate to שאת,or subordinate to the word בהרת.[something subject to disagreement in Negai-im. Ed.] This is based on Samuel I 2,36 ספחני אל אחת הכהונות “please assign me to one of the priestly duties.” Clearly, the word is used in a subordinate mode

לנגע צרעת, the area where the affliction surfaces is white skin as we know from Exodus 4,6 מצורעת כשלג, “encrusted with snowy white scales.” As we know snow is white.

אדם כי יהיה בעור בשרו, generally, such phenomena occur when one did not purify oneself from the effects of having had sexual relations or direct contact with the seed of a menstruating woman.

שאת או ספחת או בהרת, different skin afflictions, the common denominator being that they are of different shades of white. We base ourselves on the oral tradition as spelled out in Nega-im 1,1. None of these phenomena correspond to the skin diseases we read about in medical text books. Such phenomena as are mentioned in these textbooks do not result in the afflicted person being considered ritually impure, nor are they subject to the priest deciding if indeed the symptoms require isolation of the afflicted person and when such symptoms can be declared as having disappeared. According to Berachot 5 the only skin afflictions which may be viewed as G’d’s reminder to improve our lifestyle are the four kinds mentioned in our chapter. While they are not classified as afflictions revealing G’d’s love for the person thus afflicted, they are however, described as מזבח כפרה, as “an altar serving as stepping stone to atonement for the character weakness that the afflicted person has to overcome.” G’d does not employ any other medically well known skin diseases as His instrument to call us to order for various sins committed. והובא, anyone who goes to a place to be attended to is not referred to as “coming,” בא, but as being brought, i.e. הובא. Compare Psalms 45,15. The passive mode of the transitive form והגישו אדוניו in Exodus 21,6 is ונגשו אל המשפט, “he his being brought to.”