The Pulpit Commentary
The word translated plague of leprosy literally means stroke. It seems to be used in the sense of spot. Then shall he be brought unto Aaron the priest. That the regulations respecting leprosy were not sanitary arrangements, as has been sometimes represented, is indicated by the authority over the leper being vested in the priest rather than in the physician, and the question of whether a man was a leper or no being decided by the former rather than the latter. It is to be noted also that the priest is not made unclean by his contact with the leper, because he is in the performance of his duty. The supposed leper may be brought either to Aaron or unto one of his sons the priests; that is, to the high priest or to the ordinary priest, and those descendants of Aaron who were disqualified by physical infirmities from officiating at the altar were permitted to act as examiners in leprosy.

The Pulpit Commentary
When the hair in the plague is turned white. This is the first symptom, and the most noticeable as the commencement of the disease. The hair around the spot loses its colour and becomes thin and weak, the separate hairs being hardly stronger or individually thicker than down. The second symptom is when the plague in sight be deeper than the skin of his flesh; that is, below the upper skin, or cuticle, and in the real cutis. These two symptoms distinguish real leprosy from other affections which at first bear a similar appearance.

The Pulpit Commentary
In case the symptoms are not decisive, then the priest shall shut up him that hath the plague seven days. The words thus translated would perhaps be better rendered, then the priest shall bind up the part affected for seven days. The priest is to delay his judgment for a week, and, if necessary, for a second week, during which period the patient is, according to the rendering, either to be confined to his house or, more probably, to have the spot bandaged. Whether the disease be or be not leprosy will probably have declared itself by the end of that time; and if the plague be somewhat dark on the fourteenth day, that is, if it has begun to lose its colour and to fade away, and has not spread in the skin, the priest is to decide that it is not real leprosy, and pronounce the man clean. He is still, however, to be kept under supervision, and if the spot is found to spread, he is to be pronounced unclean, as it is proved to be a leprosy.

The method of procedure in the case of a doubtful leprosy having been laid down in the previous verses, the rule for dealing with an unmistakable case is here given. When the characteristic white spot and white hair are present (if the rising be white in the skin, and it have turned the hair white), and if a third symptom be present—if there be quick raw flesh in the rising, that is, if there be an ulcer underneath the white scab, there is to be no delay, as in the previous case, but judgment is to be passed at once. The priest shall pronounce him unclean, and shall not shut him up: for he is manifestly unclean.

If a leprosy break out abroad … and cover all the skin. There was a form of disease similar to true leprosy, and bearing the name of leprosy, and by some thought to be the final phase of true leprosy, which was yet not to cause legal uncleanness. It was distinguishable from the leprosy which caused uncleanness by a diffusion of the white flakes over the whole body, and by the absence of any patches bearing the appearance of raw flesh (Lev_13:12, Lev_13:13). Real leprosy might pass into this harmless kind or phase, and it was known to have done so as soon as the raw patches of flesh had disappeared (Lev_13:16, Lev_13:17). When this had taken place, the priest pronounced him clean.

The method of discriminating between a leprous spot and the reappearing scar of an old ulcer. A reappearing ulcer is to be regarded as leprous it' it have the characteristic marks of leprosy; that is, if it be below the cuticle, and the hairs round it arc turned white. If it has not these marks, it has to be watched for seven days, and if in that time it does not spread, it is to be declared a burning boil, or rather an ulcerous scar, in which case the priest shall pronounce him clean.

The method of discriminating between a leprous spot and the scar of a burn. If there be any flesh, in the skin whereof there is a hot burning. This rendering indicates that the authors of the Authorized Version thought a disease of the nature of a carbuncle to be meant; but it is better to take the words literally as they are translated in the margin, If there be any flesh, in the skin whereof there is a burning of fire; that is, a scar from a burn, The leprous spot and the scar are to be distinguished as in the previous case. An old nicer or burn is a more likely place for a leprous spot to appear than any part of the body which is sound, just as in the moral sphere sin fixes on some old wound of the soul to burst out in.

The method of discriminating between a leprous spot on the head or beard and an ulcer in the same place. The symptoms of leprosy are the same as before, except that the hairs in this case are of a reddish-yellow colour instead of white. The treatment is also the same, with the addition of shaving the head or beard except at the place where the suspicious spot has appeared. In Lev_13:31 the priest is ordered to shut up (or bandage) the patient, if

(1) the spot be only in the upper cuticle, and

(2) there is no black hair in it.

We should have expected rather from the second condition if there be black hair in it, or if there be no yellow hair in it; and Keil accordingly proposes to omit the negative or to change the word "black" for "yellow," the two words in the original being easily interchangeable. The present reading is. however. defensible. The fact of the spot being not below the cuticle was a very favorable symptom; there being no black hair was a very unfavourable symptom. Under these circumstances, the priest delays his judgment in the ordinary way.

Lev_13:38, Lev_13:39

The method of discriminating between leprous spots and freckled spots. In case the spots in the skin of theft flesh be darkish white; that is, of a dull or pale white, then it is only a freckled spot that groweth in the skin. This is "the harmless bohak (ἀλφός, LXX.), which did not defile, and which even the Arabs, who still call it bahak, consider harmless. It is an eruption upon the skin, appearing in somewhat elevated spots or rings of unequal sizes and a pale white colour, which do not change the hair; it causes no inconvenience, and lasts from two months to two years" (Keil). The man or woman who has this is clean.

Leprosy appearing on the bald head. Though leprosy makes the hair drop off around the leprous spot, baldness is in itself no sign of leprosy, whether at the back or front of the head (Lev_13:40, Lev_13:41); but as the bald head is a not unusual place for the leprous spot to appear, any eruption upon it is therefore to be watched and tested as before.

Lev_13:45, Lev_13:46

The cases for examination having been discussed, the law for the treatment of the man in whom leprosy has been proved to exist is pronounced. The leper in whom the plague is to be ex-eluded from the camp, lest others should contract defilement from him. tie is for the same reason to cry, Unclean, unclean, lest any wayfarer should unwittingly come in contact with him; and his clothes shall be rent, and his head bare, and he shall put a covering upon his upper lip, these being the signs of mourning for the dead. The bared or disheveled head (see Le Lev_10:6) and the covered lip are incidentally mentioned as signs of mourning in Eze_24:17, and the covered upper lip as a mark of shame in Mic_3:7. By the expression, He shall dwell alone, is meant he shall dwell apart from those who were clean. Of course, lepers would naturally associate with each other, and so we find that they actually did (Luk_17:12). As their presence was supposed to defile any place that they entered, they were punished in later times with forty stripes if they did not observe the restraints laid down for them. "They were, however, admitted to the synagogue, where a place was railed off for them, ten handbreadths high and four cubits wide, on condition of their entering the house of worship before the rest of the congregation and leaving it after them" (Edersheim, 'Temple Service'). The exclusion of the leper was not for the purpose of avoiding contagion, nor to serve as a penalty for having contracted so loathsome a disease, but primarily to prevent the spread of ceremonial uncleanness communicated by his touch, and typically and mystically to teach that the fate brought upon a man by unremoved sin is separation from the people of God here and hereafter.

LEPROSY IN CLOTHES (Lev_13:47-59). To account for the use of the name leprosy in this connection, an ingenious theory has been propounded that the same cause produced a like effect in the human frame in clothes and in houses. "There is here described a disease whose cause must have been of organic growth, capable of living in the human being and of creating there a foul and painful disease of contagious character, while it could also live and reproduce itself in garments of wool, linen, or skin; nay, more, it could attach itself to the walls of a house and there also effect its own reproduction. Animalcules, always capable of choice, would scarcely be found so transferable, and we are therefore justified in supposing that green or red fungi, so often seen in epidemic periods, were the protean disease of man and his garment and his house" (Dr. Mitchell, 'Five Essays'). It is not necessary to have recourse to this tempting but unproved hypothesis, inasmuch as the similarity of appearance presented by the two affections is enough to account for their going by the same name. Leprosy in garments and in leather is a mildew which cannot be got rid of, called leprosy by analogy. Like other causes of uncleanness, it makes the material unclean, because it gives a repulsive appearance to it, reminding the beholder of the disease which it resembles. "Leprosy in linen and woolen fabrics or clothes consisted in all probability in nothing but so-called mildew, which commonly arises from damp and want of air, and consists, in the case of linen, of round, partially coloured spots, which spread and gradually eat up the fabric, until it falls to pieces like mould. In leather, the mildew consists more strictly of' holes eaten in,' and is of a greenish, reddish, or whitish colour, according to the species of the delicate cryptu-gami by which it has been formed ' (Keil).

Whether it be a woolen garment, or a linen garment. Wool and flax are the two materials for clothes mentioned in Deu_22:11; Pro_31:13; Hos_2:7.

The Pulpit Commentary
Whether it be in the warp, or woof. It is hardly possible that such a fault as leprosy or mildew could appear in one set of the threads without affecting the others, provided that both were equally good when they were made up into the cloth; but it is quite possible that a heap of yarn, used either for the warp or for the woof, might have been injuriously affected before it was woven, and then the fault would naturally make its appearance where the mischief had been originally done. Whether in a skin, or in anything made of skin. An example of the first would be a sheepskin cloak; the second would designate anything made of leather.