Mikvaos, Chapter 1, Mishnah 8. Throughout this perek the Mishnah has been ascending a ladder of waters, each level possessing an advantage over the one before it. With our mishnah the count is completed: here we reach the fifth and the sixth, and highest, of the six levels of mikvaos.
One principle underlies both halachos here. A spring is not like a rainwater mikveh. Rainwater purifies only when it is gathered and standing in its place, while the water of a spring purifies even as it runs along the ground, without walls to contain it.
The fifth rung: mayim mukin
"Lema'alah meihen," higher than the mikveh listed before it, are "mayim mukin." This is the water of a spring, unmixed with any drawn water that had been gathered in a vessel, yet it is water of poor quality: too salty, or bitter, water one would not call pleasant. Despite that, "shehein metaharin bezochlin." Because it is a true ma'ayan, it purifies bezochlin, while it is flowing. It need not be enclosed and held in one place, and a person may immerse in it even as the water runs.
The sixth rung: mayim chayim
"Lema'alah meihen," higher than all of these, and the last of the six levels, are "mayim chayim": natural spring water that is clear, sweet and fit to drink. Its distinction lies in three purifications that the Torah entrusts to it alone.
- "Shehein tevilah lezavim." For a zav, not every body of water will do. Scripture sets a condition on his immersion, requiring that the washing of his body be done "bemayim chayim," in living water, and it is precisely the water our mishnah speaks of here that qualifies for that tevilah.
- "Vehazayah limtzora'im." The same water serves for the sprinkling performed in the purification procedure of a metzora, concerning which the Torah again spells out the requirement: "el keli cheres al mayim chayim."
- "Uksheirin lekadeish meihen mei chatas." It qualifies too for preparing the mixture made with the ashes of the red heifer, the mei chatas that are sprinkled upon someone who contracted tumas meis, on the third day and again on the seventh, to bring him to taharah. Here as well the Torah demands living water, instructing that "mayim chayim" be put over the ashes in a vessel.
With these three uses the Mishnah closes its ladder. From the humblest collections of water at the bottom of the chapter, each level adding one further power, we arrive at mayim chayim, the water in which the Torah invests the loftiest taharos of all.