Taharos, Chapter 4, Mishnah 7. This chapter deals with cases of safek, doubtful tumah. The mishnayos before ours presented sefeikos in which the Chachamim ruled stringently, to the point of having terumah burned. Our mishnah is the mirror image of that: "Eilu sefeikos shetiharu chachamim", these are the doubts in which the Chachamim ruled that the item is tahor. It is a short mishnah, essentially a list, and most of the items on the list are unpacked in the mishnayos that follow.
The first case is "safek mayim she'uvin lemikveh", a doubt concerning drawn water in a mikvah. This case is spelled out elsewhere, in Mikvaos, chapter 2, mishnah 3. To understand it we need the basic halachah. A kosher mikvah requires forty se'ah of water, a se'ah being a measure of volume, and forty se'ah is roughly the volume of a human body. The water must be water that has not been manipulated by human hands, rainwater, for example, as opposed to mayim she'uvin, drawn water, which is exactly what the name suggests: water that people have gathered and moved.
Once the mikvah already holds its forty se'ah of valid water, adding drawn water does not disqualify it. But if the mikvah is still short of forty se'ah and three lugin of drawn water fall into it, the mikvah is pasul, and no amount of valid water added afterward repairs it. Even if the pool eventually fills well past forty se'ah, it remains invalid.
With the halachah in place, picture the uncertainty. It is established beyond question that the pool had not yet reached its forty se'ah, yet the quantity of drawn water that entered is unknown. Should that quantity have reached the shiur of three lugin, the mikvah is disqualified; should it have fallen below that measure, the mikvah remains perfectly usable. Faced with such a question, the Chachamim took the lenient path and pronounced it tahor.
The remainder of the mishnah lists further sefeikos, each of which receives its own treatment further along in the chapter. Here they are, together with where we will meet them:
- "Safek tumah tzafah al penei hamayim", a doubt about tumah floating on the surface of water. This comes up shortly, in mishnah 8.
- "Safek mashkin letamei tamei, uletaher tahor", a doubt concerning liquids, whether they themselves became impure and whether they convey impurity to something else. This is mishnah 9.
- "Safek yadayim letamei uletaher tahor", a doubt about hands, whether they are pure or impure. Along with "safek reshus harabim", a doubt arising in the public domain, and "safek divrei sofrim", a doubt in a matter of rabbinic law, these are taken up in mishnah 11.
- "Safek chullin, safek sheratzim, safek nega'im, safek nezirus, safek bechoros": doubts regarding ordinary unconsecrated food, regarding the creeping creatures that convey tumah, regarding nega'im (whose nature we will explain in its place), regarding the nazirite vow, and regarding the firstborn offering. All of these belong to mishnah 12.
- "Safek korbanos", a doubt concerning offerings, which we will learn in mishnah 13.
So our mishnah serves as a table of contents for the leniencies of the chapter, gathering in one place the doubts in which the Chachamim ruled that the item remains pure, and giving us in full detail only the first of them, the doubt about drawn water in a mikvah. I look forward to working through the rest of the list together with you.