Leviticus 13:2

When a man shall have in the skin of his flesh a rising, a scab, or bright spot, and it be in the skin of his flesh like the plague of leprosy; then he shall be brought unto Aaron the priest, or unto one of his sons the priests:

When a man shall have in the skin ... The fact of the following rules for distinguishing the plague of leprosy being incorporated with the Hebrew code of laws proves the existence of the odious disease among that people. But a short time-little more than a year, if so long a period-had elapsed since the exodus, when symptoms of leprosy seem extensively to have appeared among them; and as they could not be very liable to such a cutaneous disorder amid their active journeyings, and in the dry open air of Arabia, the seeds of the disorder must have been laid in Egypt, where it has always been endemic. There is every reason to believe that this was the case-that the leprosy was not a family complaint, hereditary among the Hebrews; but that they got it from contact with the Egyptians, and from the unfavourable circumstances of their condition in the house of bondage. The great excitement and irritability of the skin in the hot and sandy regions of the East produce a far greater predisposition to leprosy of all kinds than in the cooler temperature of Europe; and cracks or blotches, inflammations, or even contusions of the skin, very often lead to these, to some extent, in Arabia and Palestine, but particularly, in Egypt. Besides, the subjugated and distressed state of the Hebrews in the latter country, and the nature of their employment, must have rendered them very liable to this, as well as to various other blemishes and misaffections of the skin, in the production of which there are no causes more active or powerful than a depressed state of body and mind, hard labour under a burning sun, the body constantly covered with the excoriating dust of brickfields, and an impoverished diet-to all of which the Israelites were exposed whilst under the Egyptian bondage.

It appears that, in consequence of these hardships, there was, even after they had left Egypt, a general predisposition among the Hebrews to the contagious forms of leprosy-so that it often occurred as a consequence of various other affections of the skin. And hence, all cutaneous blemishes or blains-especially such as had a tendency to terminate in leprosy-were watched with a jealous eye from the first (Good's 'Study of Medicine'). A swelling х sª'eet (H7613)], a spot or rising in the skin, a pimple х capachat (H5597)], a scab, implying the falling off of the hair, or bright spot on the skin х baheret (H934)], a white spot or depression in the skin with white hairs, created a strong ground of suspicion of a man's being attacked by the dreaded disease.

Leprosy, х tsaaraa`at (H6883)] - white leprosy, from х tsaara` (H6879)], to strike, to smite with a heavy blow. The name thus derived signifies properly a stroke or lash, and expresses the sentiment that has prevailed in all ages through the East, where this disease is almost incurable, that it is a punishment directly inflicted by the hand of God. This, we learn from many passages of Scripture, was the common opinion of the Jews; and Herodotus records it to have been the belief of the ancient Persians, that the leprosy was a punishment for having offended the sun. [The Septuagint has lepra (G3014), which comes from a word signifying a scale-the scaly disease.]

Then he shall he brought unto Aaron ... Like the Egyptian priests, the Levites united the character of physician with that of the sacred office; and on the appearance of any suspicious eruptions on the skin, the person having these was brought before the priest-not, however, to receive medical treatment, though it is not improbable that some purifying remedies might be prescribed, but to be examined with a view to those sanatory precautions which it belonged to legislation to adopt.