This evening begins Shavuot, the Feast of Weeks. The holiday extends two days here in the Diaspora until Tuesday evening an hour after sunset. I am sorry to have started this after the East Coast Kossacks are likely to see it.
In the Torah itself, Shavuot is distinguished by being at the end of a process of counting fifty days after Pesach. Shavuot is the only time that leavened offerings were brought in the Temple: a basket was brought of two leavened loaves, two unleavened loaves mixed with oil, two unleavened loaves smeared with oil, and two unleavened loaves with nothing. The Rabbis designated Shavuot as the time of the giving of the Torah. As a result, there is a custom to stay up all night and learn the first night of Shavuot. Dairy foods (an explanation is that Moses was on the mountain for forty days, and the numeric equivalent of halav, milk, is forty) are served at at least one meal. On Shavuot, the passage containing the Ten Commandments is read, and the Book of Ruth, which does not have any fixed reason either. In the Sfas Emes's discussion of Shavuot, he emphasizes the theme of the "New Year for Torah". As we learn through the night, we acquire the capacity to be creative in our Torah learning and continue the chain of Oral Law through the generations. The power to grasp the spiritual essence of the Torah becomes renewed. Our share in the Torah is judged for the year.
Another lesson of Shavuos is (and I tremble to write this after the pie ad) achdus, unity. The Jews were able to accept the Torah because they had one will to accept it and because they were not divided among themselves. Last week in parshas Bamidbar the Jews were counted by tribes as they left Mount Sinai; after having experienced complete achdus, first the Kohanim and Levites are split up from the Jewish people, and then they are once again divided into tribes. Similarly, after Moses repeats the legal contents of the Torah, which all the Jews accepted, in the book of Deuteronomy, he blesses the tribes separately. Having essentially the same goal and the same rules does not mean that everyone has to have the same character.