Lévitique 13:4

But if the bright spot be white like chalk in the skin of his flesh, and the appearance of it be not deep, with whiteness like snow rather than skin, the hair, too, not being turned to whiteness like chalk, the priest shall shut up him who is plagued seven days;

turned white Here the verb “turned” is intransitive, and means the same thing as the passive form of the transitive (i.e., “has been turned”).

deeper There is more pigment on the spot than on the skin (“deeper” here does not mean “lower”).

he will render him ritually impure verbally, by declaring that he is ritually impure

the kohen will quarantine the symptom for a week I.e., the person will be closed off. He will wait a week, for most illnesses change their course on the seventh day [comment on 12:1].

ועמוק אין מראה, it is not the same kind of white as the other kinds of scales on the skin mentioned thus far.

ועמוק אין מראה מן העור, even though the sages (Shevuot 6) have said that everything which looks white is described a looking deep, recessed, as the sun appears as if deeper than the shadow, so that the wording of our verse appears to be incompatible with the statement of the sages, seeing that the skin itself is a form of something whitish the Torah means that the relationship of the normal skin to the whiteness of the tzoraat is comparable to the appearance of the shadow to the sun. [a spot of shadow on a bright day, is after all not “black” as is the darkness of the night. In fact, compared to the darkness of the night, it might be viewed as a weak “white.” Ed.]

והסגיר הכהן, “the priest shall lock up (the afflicted person).” This will enable him subsequently to determine if the affliction has spread. If one looks at the same section of skin every day, it is difficult to notice any changes. But if one has not seen it for a period of time, any changes can be noticed immediately. It is assumed that these changes, if any, occur very gradually. When Noach was in the ark and he wished to check if the water level around him had dropped, he also allowed seven days to elapse between dispatching a raven or a dove to examine this state of affairs. (Genesis 8,10). Actually, this comparison is not valid, as in our situation the priest had already marked the outer limits on the skin of the symptoms of the afflicted person clearly. He took the additional precaution of locking that person up in order to prevent him from tampering with what he had marked. He suspected such a person of trying to mislead him at the next inspection of the nega, skin-eczema.

ועמוק, “and if deeper;” we find that the Torat Kohanim explains that the reason why the Torah wrote the unusually long “and the nega had not assumed a deeper appearance than the skin in the interval between the inspection then the afflicted person is pronounced ritually contaminated,” is that if it had not done so, we would have thought that only a spreading of the symptoms would lead the priest to declare the afflicted person as ritually contaminated. The fact that the area afflicted had not diminished, is proof that the symptoms had been that which the afflicted person himself had suspected to begin with. The Torah uses similar language when discussing symptoms of boils in verse 20 of our chapter. The wording of the entire chapter has to be understood in this vein. However, according to the explanation of Rashi, the word עמוק has to be understood as relative, i.e. like shade compared to an area lit up by the sun. This does not sound like a good comparison for the word הסגר, “locking up.” Our author admits that when speaking of north Europeans who have a very light skin the comparison is more apt. With people like that the appearance of the nega described in the Torah is not usually so much different from his normal skin colour. This sounds far fetched as we are told that the skin eczema known as baheret, is as white as snow, and what can be whiter than snow?