Everybody knows Shavu’ot is an important festival, but it doesn’t have a tractate to describe it. The others do – Pesachim, Rosh HaShanah, Yoma, Sukkah, even Megillah. There is no tractate of Chanukah, but that’s a different problem.
There is no date specified for Shavu’ot in the Torah: all we have is a law to count 49 days of the Omer and keep the 50th as a festival. Ancient days saw a debate between Pharisees and Sadducees as to when to begin the count, with the result that each group ended up with Shavu’ot on a different date.
The tradition is that Shavu’ot is the anniversary of the Revelation upon Mount Sinai, but all we hear about in the Torah is the agricultural aspect, the identification of Shavu’ot as the Day of the First Fruits.
Even the name of the festival is a problem – is it Shavu’ot, weeks, or Shevu’ot, oaths? If the second view is correct, one could argue that the festival enshrines two oaths – God’s promise that He will not abandon Israel, and Israel’s promise that it will not abandon the Torah. But Judaism prefers the first option!
In Greek it became Pentecost, fifty; Judaism called it Atzeret, conclusion, linking it to Pesach as Sukkot is linked to Sh’mini Atzeret. The idea is that Pesach gave us physical freedom but the Torah given on Sinai completes the liberation.
The story is that Shavu’ot indeed has a story. The Torah source clearly links Pesach and Shavu’ot by means of the Omer, so if we have a date for Pesach we know how to calculate Shavu’ot. True, the Sadducees argued about when the counting began, but they have been left behind by history.
When we ceased being an agricultural people we moved our emphasis to the historical, ethical and spiritual side of the three pilgrim festivals. Shavu’ot needed extra work, since the text did not precisely spell out that the giving of the Torah coincided with the festival of the First Fruits, but tradition made the connection and gave us, as Lord Jakobovits put it, a festival which “denotes the first ‘ripening’ or ‘maturing’ of Israel: through the giving of the Torah the purpose of Jewish history began to come to ‘fruition’”.