Shavuos is very different to the other Chagim.
Each Chag celebrates something, but Shavuos does not explicitly recall a particular event; the Torah simply says that when the count from Pesach is complete, there is a Chag. There tends to be a specific thematic mitzva for each Chag, yet Shavuos has no such mitzva.
The Chagim require a pilgrimage to Jerusalem, and each Jew who makes the journey must bring a sacrifice which can only be brought on the Chag. Yet Shavuos has a six-day window afterward in which people can still bring this offering. And unlike the other Chagim, the Jewish people had to prepare themsleves for three days before Sinai.
Shavuos is clearly different, but why?
The Chagim celebrate greatness and grandeur on God’s part. That He saved us; the He sheltered us; that He is particular in judgment; that He is benevolent in forgiveness. Shavuos is the exception, because it’s about us.
Moshe emphasised that people can never deserve God’s love, it is always a gift:
כִּי עַם קָדוֹשׁ אַתָּה, לה אֱלֹהֶיךָ: בְּךָ בָּחַר ה אֱלֹהֶיךָ, לִהְיוֹת לוֹ לְעַם סְגֻלָּה, מִכֹּל הָעַמִּים, אֲשֶׁר עַל-פְּנֵי הָאֲדָמָה. לֹא מֵרֻבְּכֶם מִכָּל-הָעַמִּים, חָשַׁק ה בָּכֶם–וַיִּבְחַר בָּכֶם: כִּי-אַתֶּם הַמְעַט, מִכָּל-הָעַמִּים. כִּי מֵאַהֲבַת ה אֶתְכֶם – You are a holy people to God. He has selected you to be his chosen people from all nations on the face of the earth. You have not been chosen because you are mighty; you’re not. Purely because He loves you so… (7:6-8)
It is not possible to earn something in a framework in which everything is from God. Yet God loved them all the same. Just like winning the lottery, we celebrate our good fortune. This is עצרת – “stopping” – to take stock of the monumental moment.
The Torah calls Shavuos שבועותיכם – “your Shavuos”. The Torah does not call any other Chag “yours” – not סוכותיכם, nor פתחיכם. Shavuos is the Chag of the Jewish people. It is for us and about us. . There is no mitzva, because the Chag is marked by just being ourselves. There is no mitzva, as it would confine the expression of love to a particular thing. The relationship cannot be adequately expressed through a ritual act. We simply celebrate and enjoy ourselves.
However, there is a caveat. To internalise what the Chag entails, it cannot simply be an experience. It demands an integral preparation that the others don’t; the three days of preparation. The six-day window afterward is the Char carried over to an ordinary, everyday life.
Shavuos was not the day the Torah was given. That was on Yom Kippur, when Moshe came down the second time and told them they’d been forgiven. The Midrash says that Shavuos is when Moshe ascended, and was confronted by angels, who could not abide for the Torah to be given to man, or in their parlance, “one borne of a woman”, an epithet alluding to his mundane, material existence. But God told them all that the Torah was always meant for mankind.
The speciality of Shavuos celebrates physicality because that is precisely what elevates the human being. We are holy because we are human, and our choices and achievements can mean something.
The Kotzker said it best.
God has plenty of holy angels. What He is after is holy people.