How can God's name get greater? Isn't God already as great as it gets?
The Kaddish opens with a request: may His great name be made great and holy. That sounds backward. What could God be missing?
The Tur (a law code from the 1300s) says the opening is built on a verse. At the end of a prophecy about a last great war, God says through the prophet Yechezkel: "I will show Myself great and holy, and I will be known in the eyes of many nations, and they will know that I am Hashem." What grows is not God. It is how widely He is known.
The Tur adds a second verse, from Zechariah: "On that day Hashem will be one and His name one." Rashi (the classic commentator, France, died 1105) uses that verse to explain the Shema: Hashem is our God now and not yet the God of the nations, and in the future He will be the one God for all of them.
There is a sharper version. After the war with Amalek (the nation that attacked Israel after the Exodus), the Torah writes God's name short. Rashi explains: God swore that His name is not whole until Amalek is wiped out. The Tur reports that some read this into the Kaddish itself: shemeh rabba as "may the name Yah become great," whole again. Tosafot (Gemara commentaries from France and Germany, 1100s and 1200s) rejected that reading. The Gemara quotes the line in Hebrew as "His great name," and that is all the words mean.
The Gemara also describes the other side. When Jews answer "May His great name be blessed," God nods and says: "Happy is the king who is praised this way in his house. What is there for a father who has exiled his children?" The Tur says this is why the Kaddish has the word nechemata, "consolations." God grieves over our exile, and we pray that He be consoled soon and hurry to redeem us.
So the request is not that God change. By the verse it is built on, it is that the world come to know Him, and that the exile end.
Yechezkel 38:23,Tur, Orach Chaim 56,Zechariah 14:9,Rashi on Devarim 6:4 and Shemot 17:16,Tosafot on Berakhot 3a,Berakhot 3aWhy is this in Aramaic when the rest of the siddur is in Hebrew?
Almost everything you have said so far this morning was Hebrew. Kaddish is in Aramaic, the language Jews spoke day to day in the time of the Gemara. The classic sources give two reasons, and they point in opposite directions.
The first is the well-known one. The Tur (a law code from the 1300s) brings it as "some say": the angels. The Gemara says the angels do not recognize Aramaic. Kaddish is such fine praise that they would be jealous of us. The Tur adds a part that often gets dropped. When Jews answer the main line, God is reminded of the destroyed Temple and of the exile, and if the angels understood that, they would use it to accuse us. So it is said in a language they do not follow.
Tosafot (commentaries on the Gemara by rabbis in France and Germany in the 1100s and 1200s) quote the jealousy explanation as what "people say" and turn it down in one line: there are plenty of beautiful prayers in Hebrew.
Their own answer is practical. Kaddish used to be said after the public Torah talk. Ordinary people were in the room, and not all of them understood Hebrew. So it was set in Aramaic, "which everyone understood, because that was their language." The Tur gives this answer in the name of Ri, one of the main authors of Tosafot.
Abudarham (a commentary on the prayers, Spain, around 1340) points out that it is not all Aramaic anyway. The run of praise words in the middle, yitbarakh veyishtabach and the rest, is Hebrew. His reason: the praise itself could not be changed into Aramaic.
The two reasons leave you in different places. By the first, Aramaic is there so that someone will not understand. By the second, Aramaic was chosen so that every person in the room would know what they were answering Amen to.
Tur, Orach Chaim 56,Sotah 33a,Tosafot on Berakhot 3a,Abudarham, KaddishEveryone suddenly gets loud for one line. What is the big deal?
The line is Yehe shemeh rabba mevarakh: "May His great name be blessed forever and for all time." It belongs to the room. The person saying Kaddish ends his first paragraph with "and say: Amen," and this is the answer that comes back.
The Gemara makes a huge claim about it. Rava (a sage of the Gemara in Babylonia) says that since the Temple was destroyed, each day's curse is worse than the day before. Then what keeps the world standing? Two things, the Gemara answers: the Kedushah said in the daily order of prayer (the one in Uva LeTzion, near the end of Shacharit), and the "Yehe shemeh rabba" said after a Torah talk.
Rashi (the classic commentator, France, died 1105) explains why those two. Each one joins two things: Torah learning and declaring God holy in public. And both reached everybody, scholars and people who had never learned. On Shabbat nobody was working, so all the people came to hear the speaker, and at the end they answered together.
A second Gemara: Rabbi Yehoshua ben Levi (a sage of the Gemara in the Land of Israel) says that whoever answers "Amen, yehe shemeh rabba mevarakh" with all his strength has the sentence against him torn up. What is "all his strength"? Rashi says: all his concentration. Tosafot (Gemara commentaries from France and Germany, 1100s and 1200s) give the same explanation, and then add from a midrash: when Jews say this line in a loud voice, harsh decrees are canceled.
The Shulchan Aruch (the main code of Jewish law) rules both: put your mind to it, and answer out loud. The Mishnah Berurah (a central commentary on daily Jewish law, written around 1900) gives both reasons for the voice: it wakes up the concentration, and it cancels harsh decrees. He adds a limit: do not shout so loudly that people laugh at you.
So the loudness is not there for show. This is the moment a room that has just learned something turns it into praise, and the first thing the sources ask for is that you mean it.
Sotah 49a, with Rashi,Shabbat 119b, with Rashi and Tosafot,Shulchan Aruch, Orach Chaim 56:1,Mishnah Berurah 56:5