Some Mishnaic Laws of Yom Kippur

(א) יוֹם הַכִּפּוּרִים אָסוּר בַּאֲכִילָה וּבִשְׁתִיָּה וּבִרְחִיצָה וּבְסִיכָה וּבִנְעִילַת הַסַּנְדָּל וּבְתַשְׁמִישׁ הַמִּטָּה. וְהַמֶּלֶךְ וְהַכַּלָּה יִרְחֲצוּ אֶת פְּנֵיהֶם, וְהֶחָיָה תִנְעֹל אֶת הַסַּנְדָּל, דִּבְרֵי רַבִּי אֱלִיעֶזֶר, וַחֲכָמִים אוֹסְרִין:

(ב) הָאוֹכֵל כְּכוֹתֶבֶת הַגַּסָּה, כָּמוֹהָ וּכְגַרְעִינָתָהּ, וְהַשּׁוֹתֶה מְלֹא לֻגְמָיו, חַיָּב. כָּל הָאֳכָלִין מִצְטָרְפִין לִכְכוֹתֶבֶת. כָּל הַמַּשְׁקִין מִצְטָרְפִין לִמְלֹא לֻגְמָיו. הָאוֹכֵל וְשׁוֹתֶה, אֵין מִצְטָרְפִין:

(ג) אָכַל וְשָׁתָה בְּהֶעְלֵם אַחַת, אֵינוֹ חַיָּב אֶלָּא חַטָּאת אֶחָת. אָכַל וְעָשָׂה מְלָאכָה, חַיָּב שְׁתֵּי חַטָּאוֹת. אָכַל אֳכָלִין שֶׁאֵינָן רְאוּיִין לַאֲכִילָה, וְשָׁתָה מַשְׁקִין שֶׁאֵינָן רְאוּיִין לִשְׁתִיָּה, וְשָׁתָה צִיר אוֹ מֻרְיָס, פָּטוּר:

(ד) הַתִּינוֹקוֹת, אֵין מְעַנִּין אוֹתָן בְּיוֹם הַכִּפּוּרִים, אֲבָל מְחַנְּכִין אוֹתָם לִפְנֵי שָׁנָה וְלִפְנֵי שְׁנָתַיִם, בִּשְׁבִיל שֶׁיִּהְיוּ רְגִילִין בַּמִּצְוֹת:

(ה) עֻבָּרָה שֶׁהֵרִיחָה, מַאֲכִילִין אוֹתָהּ עַד שֶׁתָּשִׁיב נַפְשָׁהּ. חוֹלֶה מַאֲכִילִין אוֹתוֹ עַל פִּי בְקִיאִין. וְאִם אֵין שָׁם בְּקִיאִין, מַאֲכִילִין אוֹתוֹ עַל פִּי עַצְמוֹ, עַד שֶׁיֹּאמַר דָּי:

(1) [On] Yom HaKippurim it is forbidden to eat, to drink, to wash, to anoint oneself, to put on sandals, or to have intercourse. A king or bride may wash their face, and a woman after childbirth may put on sandals, the words of Rabbi Eliezer. But the sages forbid it.

What is added by the discussion about the exceptions?

(2) If one eats [an amount] the size of a large date, like it and its seed, or if one drank [an amount equivalent to a] mouthful, one is liable. All foods add up to make an amount equivalent to a date, and all the liquids add up to make a mouthful. Food and drink do not add up.

Why are these rules necessary?

(3) If one ate and drank in one state of unawareness, one is not obligated to bring more than one sin-offering. But if one ate and performed labor while in one state of unawareness one is obligated for two sin-offerings. If one ate foods unfit for eating, or drank liquids unfit for drinking, or drank fish-brine or fish pickling liquid, one is not liable.

What reality is this mishna imagining?

(4) [With regard to] children: they do not “afflict” them at all on Yom HaKippurim. But they train them a year or two before in order that they become accustomed to the commandments.

Why not at all? And what does "train" mean, do you think?

(5) If a pregnant woman smelled [food on Yom Kippur], they feed her until she feels restored. A sick person is fed at the word of experts. And if no experts are there, they feed them upon their own request until they say: enough.

What questions could you ask about this mishna? What's surprising about this mishna?