Commentaire sur Le Lévitique 15:2

כי יהיה זב WHEN THERE BE A RUNNING ISSUE — One might think if there be a running issue from any portion of his body (e. g., ear, nose) he shall be unclean! Therefore it states מבשרו “from his flesh" (i.e. from some part of his flesh) and not from all parts of his flesh (the prefix מ is a partitive מ). Now, however, that Scripture has made a difference between one part of his flesh and another part of his flesh, I have the right to draw a conclusion: it (the Torah) pronounces uncleanness in a case of a man with a running issue (זב) and it pronounces uncleanness in a particular case of a woman with a running issue (זבה). How is it in the case of a זבה? Through that place in her body where she becomes unclean with a lighter uncleanness, viz., that of a נדה, she also becomes unclean with a more stringent uncleanness i.e. through זיבה, a continuance of the issue beyond the usual period! Similarly the זב: through the place where he becomes unclean with a lighter uncleanness, viz., קרי, (an involuntary emission of semen which makes him unclean only until evening; cf. v. 16), he also becomes unclean through a more stringent uncleanness, viz., זיבה (when he is unclean seven days and must bring a sacrifice; cf. vv. 13 ff. with 16 ff.; from the latter it is evident which part of the body is in question; it follows logically that the same part is here intended) (Sifra, Metzora Parashat Zavim, Section 1 5).

זב מבשרו, the Talmud K’ritut 8 already explained the preposition מ in the word מבשרו as meaning “emanating from,” and not as “due to, on account of.” The word בשר refers to the male organ. In other words, unless the symptoms described here are due to a local physiological imbalance and not as a secondary effect of some other primary cause such as overeating, for instance, these symptoms will not result in and confer ritual impurity.
Our sages in Niddah 35 already explained that the symptom called זוב is very similar in appearance to the albumen in an egg which has become rotten. When the cause is directly connected to the male organs of the afflicted person the legislation under discussion in this chapter applies. This is the meaning of the word מבשרו, a disturbance in the male organ to function properly. The author speculates that the cause may be overly frequent indulgence in the sex act, which in turns leads to insufficient time for the seminal fluid being replaced properly, etc. If that were the cause, a cause brought about by fantasizing about the sex act too often, the remedy, in part, would be the seven days during which the afflicted person counts towards his being healed, reflecting on the part his lifestyle played in causing the symptoms from which he suffered. By indulging in fewer sexual fantasies and the need to offer a sin offering after being free from these symptoms the afflicted person my be on the way to spiritual rehabilitation also. These thoughts are reflected in the Talmud on the folios we referred to.

דברו אל בני ישראל ואמרתם, "speak to the children of Israel and say to them, etc." This entire verse appears redundant in view of verse 1 before it. Perhaps we may understand it in light of Torat Kohanim which explained that whereas the Israelites confer ritual impurity when they suffer from the involuntary seminal emissions called זיבה, the Gentiles do not confer such ritual impurity if they come into contact with Jews or touch their belongings, etc. The Torah therefore employed the expression דברו to indicate the relative severity of this legislation. Expressions such as דבר always indicate some degree of harshness when compared to the expression אמור. A Jew suffering from this disease transmits ritual impurity to anything he sits on or lies on, even. The Torah continued with the softer ואמרתם to console the Israelites that the fact that they transmit ritual impurity is a compliment for them as it shows that prior to that disease they were in a state of ritual purity, a status never enjoyed by Gentiles. The word אמר is used as indicating spiritual superiority in Deut. 26,17 where G'd described the mutual bond between G'd and Israel in those terms. The considerations we have just outlined form the mystical dimension of the statement in Shabbat 13 that a שוטה, a person of unsound mind, does not suffer afflictions. The meaning is that he does not realise that he is discriminated against by suffering what others do not suffer.