Why does the Torah add the prefix 'Vav' to "ve'Ish Ki Seitzei mimenu ... "?
Nidah, 32b: To incorporate a boy of nine 1 in the Din of Tum'as Keri.
Since, before that, he is not capable of fathering children. See Torah Temimah, note 61.
At which stage does a man become a Tamei Tum'as Keri?
Nidah, 43a: Only after the Zera leaes his body
Why does the Torah use the expression of "Ki Seitzei mimenu ... "?
Targum Yonasan: Because it is referring to a case of Shogeg. 1
The Ibn Ezra also learns the Pasuk in this way, and the Avi Eizer explains that this is because the Torah does not refer to Resha'im.
What is the Halachic difference between the Ba'al Keri mentioned in this Pasuk and the Zav mentioned in the previous Parshah?
Sifsei Chachamim: A Ba'al Keri is only Metamei for one day) via touching, whereas a Zav after his second sighting, is also Metamei via carrying and via Mishkav and Moshav (and requires seven clean days).
Why does the Torah write "ba'Mayim" (with a Patach)?
Rashi (in Chagigah, 11a): It implies special water
What are the implications of the seemingly excessive Lashon "Verachatz ba'Mayim es kol Besaro"?
Eruvin, 4b: The phrase per se implies that - one's entire body must touch the water (without a Chatzitzah); "ba'Mayim"
Why is a Ba'al Keri Tamei (even when it is through intimacy with his wife and not through sin)?
Ramban (on Pasuk 11): Because, not knowing whether a baby will be born from the Zera or whether it will go to waste - it is like a body from which the Neshamah has been withdrawn. 1
Seforno (on Pasuk 32): Because an emission of Zera inevitably comes through improper intentions (not in order to have children or to fulfil the Mitzvah of Onah with one's wife), due to the sin that came through the snake.
Ramban: In which case it is similar to Tum'as Meis (See R. Chavel's footnotes).
Why does it say here "Kol Besaro"? Also a Zav must immerse his entire body!
Ha'amek Davar, citing the Ra'avad: This hints that the Shi'ur for a Mikveh is enough for him to stand in (three Amos by one Amah by one Amah). A Zav immerses in a spring, and not in a Mikveh.
