Parah, Chapter 5, Mishnah 4. This chapter deals with the vessels used in preparing the waters of the chatas, the water mixed with the ashes of the parah adumah. Our mishnah opens with a dispute about a newly made vessel, and then moves to a different question altogether: which people are qualified to perform the sanctification of the water.
The mishnah opens with the words "Shfoferes shechatchah lechatas": a reed tube trimmed to serve the needs of the chatas. This is a stalk of reed shaped into a utensil so that it is able to hold the ashes of the parah adumah. "Rebbi Eliezer omer, yatbil miyad" - according to Rebbi Eliezer, one dips it in a mikveh straight away, with no prior contact with tumah at all, and by virtue of that dipping it carries the standing of a tevul yom, whose immersion has already taken place but whose day has not yet concluded. "Rebbi Yehoshua omer, yetamei ve'yatbil" - in Rebbi Yehoshua's view, tumah must be conveyed to the tube first, and the immersion comes only afterward.
What is at stake in this disagreement? Rebbi Yehoshua wants the tumah to be real and deliberate, so that the immersion that follows is a genuine purification and the vessel is unmistakably a tevul yom. The purpose is public and polemical: to demonstrate to the Tzedukim that the service of the parah adumah is indeed carried out by a tevul yom, a point we have met before in this masechta as a standing point of contention with them.
Who is fit to sanctify
The mishnah continues: "Hakol kesheirim lekadesh, chutz meicheiresh, shoteh vekatan" - everyone is fit to perform the sanctification of the water, except for a cheiresh (a deaf-mute), a shoteh (one who is not of sound mind), and a katan (a minor). These three lack the legal capacity that the act demands.
"Rebbi Yehudah machshir bekatan, u'posel b'ishah u'v'androginus" - Rebbi Yehudah declares a minor fit, and instead disqualifies a woman and an androginus.
Rebbi Yehudah's ruling, as the Gemara explains it, grows out of close attention to the wording of the pesukim. Were the sanctification of the water meant to follow the very same standards that govern the collecting of the ashes, Scripture would have used the singular form "velakach", meaning "he shall take", parallel to "ve'asaf", "he shall gather". The Torah chose instead the plural "velakchu", "they shall take". That wider formulation comes to include someone who is barred from the gathering, that is, a minor, and to declare him valid for the sanctification.
A woman, on the other hand, is left out, since the pasuk uses the masculine form "venasan", meaning "he shall place", and not the feminine "venasnah", "she shall place".
As for the androginus, one who bears both male and female characteristics, the female aspect is enough to disqualify. By contrast, a tumtum, whose gender is simply undetermined and who displays neither set of characteristics, would not be disqualified on this account.
So the mishnah has given us two halves of one concern: the vessel that receives the ashes must be brought into a state that visibly conforms to the Torah's law as Chazal understood it, and the person who performs the sanctification must be someone whom the verses include.