Kommentar zu Wajikra 15:32

זאת תורת הזב THIS IS THE LAW OF HIM THAT HATH AN ISSUE, i.e. anyone who has but one appearance of flux. And what is his law?

זאת תורת הזב, the following considerations dealing with our subject need to be kept in mind: 1) seeing that the male afflicted with the discharge in question is required to bring a sin offering at the termination of the healing process teaches that the affliction was due to sin both in deed and in thought.
2) ואשר תצא ממנו שכבת זרע לטמאה בה the fact that ejaculation of seminal fluid by a man results in his becoming ritually impure is due to the contamination of man the species by the original serpent, for ever since the original sin seminal ejaculation has been used for physical gratification also, not only for the function allocated to it by G’d, propagation of the species. Had it not been for the serpent’s seduction of Eve, nothing spiritually negative would have become part of the act of ejaculating seminal fluids.

ואשר תצא ממנו שכבת זרע, he is like him to whom a pollution happened: he is unclean with an uncleanness lasting only till the evening (Sifra, Metzora Parashat Zavim, Chapter 9 8; cf. v. 16).