The Mishnah on today’s page of Talmud describes the preparations undertaken by the Cohen Gadol (High Priest) serving at the Temple in Jerusalem, in the run up to the holiest day of the year, Yom Kippur, the Day of Atonement:
וימא יח, א
כל שִׁבְעַת הַיָּמִים לֹא הָיוּ מוֹנְעִין מִמֶּנּוּ מַאֲכָל וּמִשְׁתֶּה, עֶרֶב יוֹם הַכִּפּוּרִים עִם חֲשֵׁיכָה לֹא הָיוּ מַנִּיחִין אוֹתוֹ לֶאֱכוֹל הַרְבֵּה, מִפְּנֵי שֶׁהַמַּאֲכָל מֵבִיא אֶת הַשֵּׁינָה
For seven days before Yom Kippur they would not withhold any food or drink from the Cohen Gadol that he desired. However, on Yom Kippur eve at nightfall, they would not allow him to eat a great deal because food induces sleep [and they did not allow him to sleep].
The Talmud explains why the Cohen Gadol was not allowed to sleep:
תַּנְיָא, רַבִּי יְהוּדָה בֶּן נָקוֹסָא אוֹמֵר: מַאֲכִילִין אוֹתוֹ סְלָתוֹת וּבֵיצִים כְּדֵי לְמַסְמְסוֹ. אָמְרוּ לוֹ: כל שֶׁכֵּן שֶׁאַתָּה מְבִיאוֹ לִידֵי חִימּוּם
…Rabbi Yehuda ben Nekosa says: On Yom Kippur eve they feed him fine flour and eggs in order to loosen his bowels, so that he will not need to relieve himself on Yom Kippur. They said to Rabbi Yehuda ben Nekosa: In feeding him those foods, all the more so that you bring him to a state of arousal. [Feeding him those foods is antithetical to the efforts to prevent the High Priest from becoming impure, as they are liable to cause him to experience a seminal emission.]
How to Prevent a nocturnal Seminal Emission
Leaving aside the dispute about the details, the goal of the menu was not in question. It was to prevent the Cohen Gadol from a nocturnal seminal emission. Actually the menu was also important, as we read later on:
לֹא אֶתְרוֹג, וְלֹא בֵּיצִים, וְלֹא בָּשָׂר שָׁמֵן, וְלֹא יַיִן יָשָׁן. וְיֵשׁ אוֹמְרִים: אַף לֹא יַיִן לָבָן, מִפְּנֵי שֶׁהַיַּיִן לָבָן מֵבִיא אֶת הָאָדָם לִידֵי טוּמְאָה
They do not feed him citrons, eggs or aged wine, and some say they also do not feed him white wine, because white wine causes a person to become ritually impure through a seminal emission…
דְּתָנוּ רַבָּנַן: חֲמִשָּׁה דְּבָרִים מְבִיאִים אֶת הָאָדָם לִידֵי טוּמְאָה, וְאֵלּוּ הֵן: הַשּׁוּם וְהַשַּׁחֲלַיִם וַחֲלֹגְלוֹגוֹת וְהַבֵּיצִים וְהַגַּרְגִּיר
…The Sages taught: Five food items bring a man to a state of impurity due to emission. And these are: Garlic, cress, purslane, eggs, and arugula.
And then comes this helpful advice, unrelated to Yom Kippur:
אָמַר רַב גִּידֵּל אָמַר רַב: אַכְסְנַאי לֹא יֹאכַל בֵּיצִים, וְלֹא יִישַׁן בְּטַלִּיתוֹ שֶׁל בַּעַל הַבַּיִת
Rav Giddel said that Rav said: A guest should neither eat eggs, because they lead to a seminal emission, nor sleep in a garment belonging to the homeowner, his host, because if he experiences a seminal emission and it gets on the garment, he will be diminished in the estimation of his host…
Now back to the main attraction. The next Mishnah outlines how the night of Yom Kippur was spent keeping the Cohen Gadol awake:
יומא יח, ב
אִם (הוּא) הָיָה חָכָם — דּוֹרֵשׁ, וְאִם לָאו — תַּלְמִידֵי חֲכָמִים דּוֹרְשִׁים לְפָנָיו. וְאִם רָגִיל לִקְרוֹת — קוֹרֵא, וְאִם לָאו — קוֹרִין לְפָנָיו. וּבַמֶּה קוֹרִין לְפָנָיו: בְּאִיּוֹב וּבְעֶזְרָא וּבְדִבְרֵי הַיָּמִים. זְכַרְיָה בֶּן קְבוּטָל אוֹמֵר: פְּעָמִים הַרְבֵּה קָרִיתִי לְפָנָיו בְּדָנִיֵּאל.
If he was a scholar, he would teach Torah. If he was not a scholar, Torah scholars would teach Torah before him. And if he was accustomed to read the Bible, he would read; and if he was not, they would read the Bible before him. And what books would they read before him to pique his interest so that he would not fall asleep? They would read from Job, and from Ezra, and from Chronicles. Zekharya, son of Kevutal, says: Many times I read before him from the book of Daniel.
Rashi reminds us why all of this was necessary:
אם היה חכם דורש - בדבר הלכה כל ליל יוה"כ שלא יישן ויראה קרי
If he was a scholar, he would teach Torah - words of Jewish law throughout the night of Yom Kippur, so that he does not falls asleep and possibly have a seminal emission.
Later in this tractate (36a) the Talmud states that one of the sacrifices on Yom Kippur was performed in an unusual location in the Temple. It took place there משום חולשה דכהן גדולֹ - “because the Cohen Gadol was weak” and the new location would save him from the need to carry the sacrificial blood a few more steps. But this concern for the “weakness of the Cohen Gadol seems counterintuitive. On the one hand, he is made to stay awake for the entire night in order to prevent the remote possibility of a nocturnal seminal emission. This was an enormous physical imposition. As an emergency physician I worked hundreds of night shifts and can attest to how physically draining they are. (For those of you who want a sense of this, remember the last time you took an overnight flight. How did you feel coming off the plane?) And on the other hand we go to unusual efforts to minimize any unnecessary physical activity that he might be required to do.
All this demonstrates that the Talmudic concern for a Cohanic nocturnal emission was extremely serious. For this reason several interventions were put in place to prevent this possibility, even though they seem to be in themselves onerous.ּ But we are not quite done yet.
no one got any sleep on the night of yom kippur
יומא יט, ב
מַתְנִי׳ בִּקֵּשׁ לְהִתְנַמְנֵם, פִּרְחֵי כְהוּנָּה מַכִּין לְפָנָיו בְּאֶצְבַּע צְרָדָא, וְאוֹמְרִים לוֹ: אִישִׁי כֹּהֵן גָּדוֹל! עֲמוֹד וְהָפֵג אַחַת עַל הָרִצְפָּה. וּמַעֲסִיקִין אוֹתוֹ עַד שֶׁיַּגִּיעַ זְמַן הַשְּׁחִיטָה.