My chavruta [study partner] and I recently completed Masechet Megillah (one of the tractates, or “webs”, of the Talmud). We’ll have a formal siyum sometime this summer in NYC, and you’re all invited.
On the penultimate page, there’s a timely section that relates to how we prepare for Shavuot. The general topic is Torah readings for various times of the year. (This is the primary source for the holiday Torah readings that are read to this day.) Rabbi Shimon ben Elazar brings a tradition that Ezra established that we should read the curses in Leviticus 26 before Shavuot, and the curses in Deuteronomy 28 before Rosh Hashanah. Sure, enough this is what we still do: our calendar is rigged so that Parshat Bechukotai (containing Leviticus 26), which we read last week, always comes up about two weeks before Shavuot, and Parshat Ki Tavo (containing Deuteronomy 28), always comes up two weeks before Rosh Hashanah.

(Was anyone in Ezra’s time really using the annual cycle that we use today, where we complete the Torah in one year, starting and ending on Shemini Atzeret, so that the timing would work out this way? Probably not. But that’s not the point. Ezra was the one who originated the whole practice of public Torah reading, so the point of ascribing this particular tradition to him is simply to say that it’s really really important, as if it goes all the way back.)
So what’s the reason for reading the blessings and curses at these times of the year? If I were to guess, I would say that it makes the most sense to read about the consequences of observing or not observing the mitzvot during the High Holiday season, when we are examining our actions and preparing to repent, and before Shavuot, when we (individually and collectively) are preparing to receive Torah. (Let’s not get bogged down in the specific rewards and punishments listed in the Torah, or the question of whether we think that this is how God operates in the world. The point is that our actions, good and bad, have real consequences in the world, whether on the personal scale associated with Rosh Hashanah or the grander scale associated with Shavuot.)
But that’s actually not the reason that the Talmud gives. (Maybe that’s because the idea of Shavuot as the time of the giving of the Torah wasn’t so firmly established yet. This idea appears nowhere in the Torah or the Mishnah (though it does appear in tannaitic material in the Gemara). Shavuot’s transformation from primarily a harvest festival to primarily a Torah festival was gradual and uneven.) The Talmud’s reason? Tichleh shanah v’kileloteha. Let the year end, along with its curses. (This line, which is also the refrain of a medieval poem, gets quoted all the time around Rosh Hashanah, especially at the end of a bad year, especially especially on the Rosh Hashanah that began on September 17, 2001, but I didn’t realize until now that it came straight from the Gemara.) In other words, read all the curses before Rosh Hashanah, to get them out of the way, so that we don’t go into the new year with curses hanging over our heads.
Not such a bad idea. But (the ever-vigilant anonymous voice of the Talmud retorts) that only applies to Rosh Hashanah. What about Shavuot? Is Shavuot a new year???
Actually (the not-to-be-outdone anonymous voice of the Talmud responds) yes it is. A mishnah in Masechet Rosh Hashanah says that the world is judged 4 times a year. Rosh Hashanah is the one you’ve heard of, when God judges each person one by one. But there’s more in the world than just people. Shavuot, the feast of the first fruits, is when God judges the fruits of the coming year and decides whether it’s going to be a good crop or a bad crop. So the idea of getting all the curses out of the way also applies to Shavuot, since we want this year’s crop to be fruitful.
As we prepare for Shavuot (we’re on day 45!!! 90% of the way to 50!), whether we understand it as the festival of the first fruits or the festival of the giving of the Torah, let’s consider all of the possible blessings and curses, and make this year a year of blessing! Happy new year!