Why do Ashkenazim have a Minhag to eat Milchigs (dairy) on Shavuos?
Seven answers from Aish HaTorah:
- They just got the laws of kosher slaughter and weren't yet prepared.
- Torah is likened to milk.
- Gematria of Chalav is 40 and Moshe Rabbeinu was on Har Sinai for 40 days.
- Because bikkurim is joined to the command to not eat meat and milk together (so eat two meals, one meat and one dairy; I had not heard this before now).
- An alternate name for Har Sinai is Har Gav'nunim, which is linguistically related to milk. Also, gematria of "gevina" is 70, for the 70 faces of the torah.
- To comemorate Moshe being nursed by his mother under Paro's nose.
- This may have been the first time Jews ate dairy, since some say that until the Torah explicitly permitted it, milk was considered a limb of a living animal, and forbidden under the 7 Noahide laws.
And another one (Rama OC 494): the special sacrifice on Shavuot were two loaves of bread. By eating two meals, one meat one dairy, you're forced to have two separate loaves of bread (total) for them.
I believe there's another one from the Zohar about how when blood runs through the mammary glands and is converted to milk, this represents the turning from G-d's wrath (blood) to mercy (milk), which happened as the Jews accepted the Torah. (This is also neat as the Talmud says the ratio of Divine strict justice to mercy is 1:500, (based on Exodus 20:5-6); well wouldn't you know it, but according to this anatomy lecture,
On avg. 400 - 500 units of blood passes through the udder for each unit of milk synthesized by a high producing dairy cow
An interesting distinction among these answers is that according to some of them, you're just as well-off (maybe even better) eating only dairy on Shavuot (assuming ice cream makes you just as happy as steak); according to the first answer above, Alex's, and Monica/Aish #4, you should purposely have meat one meal too.
Another one: eating milk, then waiting before eating a meat meal, shows that we are more scrupulous in the laws of kashrus than the angels (who ate both at Avraham's house), and therefore we deserve to receive the Torah (as against their argument that it should be kept in heaven).
Along the one-dairy-meal-then-one-meat-one referenced by others: The event that took place at Matan Torah was of dual significance. While we were given the "Torah Shel Mata" (Torah for down here) its counterpart, the "Torah Shel Ma'ala", stayed up there (just like the parallels between the world down here and the world up there described in the Zohar).
The Torah is the paradigm of things a person benefits from marginally in this world, with the primary benefit awaiting him in the world to come (משנה פאה א:א). We reflect this fact by eating the marginal animal product (milk) earlier in the chag and the primary animal product (meat) later.
See Sefer יומא דעצרתא which gives 32 reasons why we eat dairy on Shavuos in the section ייני אם חלבי. Among them are:
- (reason 18) we try to minimize our Simcha since David Hamelech died then.
- (reason 29) through the Torah we can conquer the Yetzer Hara and reach לבי חלל בקרבי which is Rashei Teivos חלב.
- (reason 30) the flavor of milk changes based on the food the mother ate, so too our Torah is sweeter if we act with Kedusha.
- (reason 11) the Baysusim wanted Shavuos to always be on Sunday because they read Miamacharas Hashabbos literally, if it was on Shabbos you couldn't have milk on Shavuos because they couldn't milk on Yom Tov or Erev Yom Tov since that would be Shabbos, and the milk from Friday would have been bad without refrigeration. We eat milk to show that we could milk on Erev Yom Tov to show that Shavuos doesn't have to be on Sunday.
- (reason 3) Taanis 7a writes that milk only lasts in humble Keilim, so too Torah only lasts in a humble person.
See more there, every reason is fully explained and sourced.