What is the question "Mi Yode'a?"?
Rav Sadya Gaon: Which [living beings] know that man's Ru'ach goes above, and an animal's Ru'ach is lowered below?
Rashi: This is like "Mi Yode'a Yashuv" (Yo'el 2:14. It is not a question, rather, a statement - one who knows, will repent. Also here,) one who understands and puts to his heart that man's Ru'ach goes above and is judged, and an animal's Ru'ach goes below and need not account for its deeds, he must not act like an animal that is not particular about its deeds.
Ibn Ezra: "Ha'Olah" and "ha'Yoredes" do not begin questions 1 . The verse asks, who knows among people, the difference between Ru'ach ha'Adam and Ru'ach ha'Behemah. Knowledge of the Ru'ach is deep, and it needs proofs. The only ones who can understand even a little, are sages who clarified their thoughts with the scales of Chachmah and its four foundations. The Torah mentions the water and land bringing forth "Nefesh" and "Nefesh Chayah". Regarding man's creation, it does not say Nefesh Adam, rather, "Na'aseh Adam b'Tzalmenu", "va'Yipach b'Apav Nishmas Chayim" (Bereishis 1:26, 2:7). Chayim hints that it persists, and does not perish like Nefesh Behemah. In Tanach, Neshamah applies only to man, e.g. "Nosen Neshamah la'Am Aleha" (Yeshayah 42:5). "Kol Asher Nishmas Ru'ach Chayim b'Apav" (Bereishis 7:22) refers only to man. Shlomo says at the end of this Sefer that man's Ru'ach "Tashuv El ha'Elokim" (12:7), and not to earth.
Rashbam: This refers to "v'Ru'ach Echad la'Kol" (19). I say that there is one Ru'ach for both of them, for who knows if man's Ru'ach goes above and an animal's goes below?! I say that they have the same Ru'ach, and all is Hevel; man has no advantage over animals.
Ri Kara: Man's Ru'ach that goes above - who knows what happens to it, that it does not return to creations? Also an animal's Ru'ach that goes below to the ground - what happens to it? I can search for the body, for it return to the earth. Who can search after the Ru'ach, to know where is its rest?
Rid: "Ha'Olah" and "ha'Yoredes" do not begin questions, for then there would be under the Hei a Patach with a Sheva. Also, below it says "veha'Ru'ach Tashuv El ha'Elokim Asher Nesanah" (12:7) - it is known! Rather, it is Hei ha'Yedi'ah. Surely Ru'ach Adam ascends and Ru'ach Behemah descends. Who knows this as clear as something sensed, that he can say 'I am better than an animal, for my Ru'ach ascends to Shamayim'?
R. Avigdor: One who puts his heart, he knows this clearly. This is like "Mi Yode'a Yashuv" (Yo'el 2:14; it is not a question). "Ha'Olah?" is not a question, for there is a Kamatz under the Hei. Rather, clearly it ascends - "veha'Ru'ach Tashuv El ha'Elokim Asher Nesanah" (12:7). Ru'ach Behemah is a Rasha's Neshamah. He was not concerned for his deeds, like an animal. Ru'ach Adam ascends and returns to the place from where it was 'hewn' - "va'Yipach b'Apav Nishmas Chayim" (Bereishis 2:7). Ru'ach Behemah returns to the place from where it was 'hewn' - "Totzei ha'Aretz Nefesh Chayah l'Minah" (ibid. 1:24). The Neshamah is blown with Hashem's Ru'ach Kodesh, for "Ner Hashem Nishmas Adam" (Mishlei 20:27) 2 . Man's Neshamah is Chachmah and Da'as - "v'Nishmas Shakai Tevinem" (Iyov 32:8). It is put in the place where a baby's brain is soft. It makes the body move, and warms it. It resembles its Creator. It sees and is not seen. It does not eat. However, it benefits from nice smells - "Rei'ach Nicho'ach la'Shem" (Vayikra 1:9). Therefore it says "Kol ha'Neshamah Tehalel Kah" (Tehilim 150:6). The Neshamah is like its Creator, who made it white, clean and clear. It has no image, like its Creator.
Seforno: Who strives to know the intellectual Ru'ach of man? It goes above to a level of eternal happiness. It is proper to conduct with it in investigation and in deed. [And who strives to know] the animalistic Ru'ach, which descends? It is proper to distance from it.
Metzudas David: Few are wise to know the difference between the esteemed Ru'ach of Adam, which ascends after death to the source from which it was hewn; Ru'ach Behemah returns to the place from where it was hewn. Since few are wise to understand this, this shows that they are [like] animals.
Ibn Ezra: Hei ha'Yedi'ah (to identify, like 'the'), if the following letter is Aleph, Ches, Hei, Ayin ha'Ra or Reish, usually the Hei has a Kamatz [and sometimes a Patach]. The prefix Hei that introduces a question always has a Patach under it. "Ha'Olah" has a Kamatz (so it ha'Yedi'ah). Also the Hei in "ha'Yoredes" is ha'Yedi'ah, for there is a Dagesh after it, like "ha'Yosheves" (Shir ha'Shirim 8:13); if it was a question, there would not be a Dagesh after it, and there would be under the Hei a Patach with a Sheva. (Magihah in Toras Chayim - sometimes it is Patach Katan (Segol).)
R. Avigdor: This is why man dreams. The animalistic brain that dwells in the blood, which is his Nefesh - "Damo v'Nafsho Hu" (Vayikra 17:14), when he sleeps, the Neshamah, which is from above, leaves via his nostrils and goes around the entire world in the hand of the angel Dumah, the Sar of Nefashos. It returns and tells its friends - the animalistic Ru'ach still inside the body, like it swore to it [to tell it] when they were created in the body. Sometimes it tells it what is found far away, when it flew in the angel's hand, and it tells it via a hint. Therefore, a dream needs interpretation, for sometimes it is a hint. The Ru'ach is in the heart, which does not sleep; the dream comes to it. The Neshamah, which flew via the angel, tells the Ru'ach - "Ani Yeshenah v'Libi Er" (Shir ha'Shirim 5:2). An animal does not have Nishmas Ru'ach Chayim, so it never dreams.
How do the Neshamah and Ru'ach leave the body, and what happens to them?
R. Avigdor: When it is time for the Neshamah to leave, when man dies, the angel [of death] confounds the body until he opens his mouth, and he throws in a bitter drop. The Neshamah is uprooted until the mouth. He breathes great breaths amidst great bitterness and pain. The angel sends its hand and takes the Neshamah from his mouth, and he dies. The Ru'ach dwells in the nose until it decays. After, it is given to Dumah, the Sar of Nefashos. It takes it to Chatzermaves - a yard surrounded with a stone wall. A river is in front of the Chatzer, and a field is in front of the river. For Tzadikim, for 12 months, every day Dumah takes Ruchos and wets them in the river, and they smell the herbs of the field. Afterwards it ascends to the bind of life - "v'Haysah Nefesh Adoni Tzerurah bi'Tzror ha'Chayim" (Shmuel I, 25:29). Resha'im's Neshamos immediately descend to Gehinom. "V'Es Nefesh Oyvecha Yekal'enah" (ibid.) - their Neshamos are slung from east to west and from north to south - "b'Yom Ridto She'olah" (Yechezkel 31:15).