Since the Temple was destroyed and the festival of first fruits lost its land base, the various customs practiced by our fathers in their homeland were gradually diminished, and replaced by several others, designed to affirm the remembrance of the giving of the Torah at Mt. Sinai.
It should be noted that in the Bible there is no mention of the giving of the Torah; nevertheless, scholars calculated and determined it based on Exodus 19: “In the third month, when the children of Israel were gone forth out of the land of Egypt... and there Israel camped before the mount.” According to this, the third month from Nisan is Sivan, and the revelation occurred on the sixth of that month.

 

Rabbi Menachem Mendel of Kotzk used to say: The festival of Shavuot is called “the time of the giving of our Torah” and not “the time of receiving our Torah.” The Torah was given equally to all of Israel; however, it is not received equally by each person in Israel: Rather, each individual receives the Torah according to his worth and comprehension...