The pinnacle of the Yom Kippur service, in which the high priest enters the Holy of Holies, is a private act. When the priest enters that awesomely sacred space to atone on behalf of the whole community, he does so alone.
Other aspects of the Yom Kippur service, however, are public — extremely public. Here’s an excerpt from a mishnah on yesterday’s page:
Five immersions and ten sanctifications the high priest immerses and sanctifies on Yom Kippur. And all in the sacred area (the Temple courtyard), on the roof of the Hall of Parva, except for this first immersion alone. They spread a sheet of fine linen between him and the people and then the high priest immerses and sanctifies his hands and feet.
Then as now there were five Yom Kippur services, and between each the high priest would disrobe and immerse in a mikveh. What is striking about this mishnah is where this immersion takes place: on the roof of the Hall of Parva. Back on Yoma 19a, we learned that this was the room used for salting the consecrated hides that belonged to the priests to prevent them from spoiling. In this case, the use of the room is not as important as its location. Putting the priest on a rooftop positions him up high, so everyone can witness his ablutions. On this most sacred day of the year, just as the people stand with their souls bared before God, the priest literally stands naked before the community. A linen cloth maintains his modesty, but otherwise his immersion is as public as possible. It’s an act of radical transparency.
The mishnah notes that the first immersion does not take place within the Temple courtyard, but just outside the Temple, preparing the priest to enter. This immersion, too, is done publicly and also way up high. As the Gemara explains on today’s daf, the priest takes his first immersion on top of the Water Gate of the Temple.
The gate, of course, was not just a door on a hinge, but a small building through which one would pass to enter the Temple. The Gemara brings another mishnah that gives us the rabbis’ best reckoning of its size: 20 cubits (or about 30 feet) high, and ten cubits (15 feet) wide. In contemporary terms, about three stories.
A mikveh must be fed by live waters. How did the ancients get flowing water up to the top of a Temple gate? The Gemara explains that the mikveh was fed by the Eitam Spring, which was located a little more than 10 kilometers south of Jerusalem near Solomon’s pools at an elevation of about 23 cubits (about 35 feet) higher than the Temple. An aqueduct, whose archaeological remains were discovered not so long ago, transported this water all the way to the Water Gate in Jerusalem. Having finally made this long journey, the water poured into a small pool on the smooth, marble roof of the gate so that before all the people on whose behalf he performed the ritual, and hidden only by a fine linen sheet, the high priest could shed his garments, immerse himself and emerge ready to ask for God’s atonement.
Read all of Yoma 31 on Sefaria.