Excerpted from Celebrate! The Complete Jewish Holiday Handbook. Reprinted with permission of the publisher (Jason Aronson Inc).
In the weeks before Shavuot in 1096 the Crusades began, claiming hundreds of Jewish lives in the Rhine valley. To honor the dead without interfering with the joy associated with the holiday, a communal prayer for those martyred in that barbaric outbreak of anti-Semitism was introduced for the Sabbath prior to Shavuot. The timing was considered doubly significant, because the day fell during the Omer period, which commemorates the massacre of an earlier persecution, that of Akiva’s students by the Romans. Along with Av Harachamim (Father of Compassion), the first form of the memorial prayer, the list of the rampage’s victims was read.
Since more people attended synagogue on Shavuot than on the Shabbat prior to it, the memorial service was moved to the holiday itself and expanded to
encompass the one done on Yom Kippur since talmudic days, which honored all dead, not only martyrs but also pious Jews and deceased loved ones. (In time, it was added to the liturgies of the last days of the other pilgrim festivals as well).
When Simchat Torah developed several centuries later, the intense expression of joy for Torah was shifted to that occasion. It was not that the people of the time felt that the beginning of our covenantal life had lost any significance, they recognized that, as in a good marriage, depth of understanding and appreciation for one’s partner a grows over time. The love and attachment at a 25th or 50th wedding anniversary is more substantial, and more substantiated, than at the wedding. So, too, there is more reason for joyous celebration after the Torah has been examined, studied, and lived with than when it has merely been presented.
For the kabbalists [mystics], in particular, though, Shavuot remained an opportunity to express intense devotion to Torah. A midrash [commentary] says that even though the Israelites knew that God was going to give them an incredible gift on the afternoon of Sivan 6, at noon they were still asleep. Moses had to go to their shelters (according to one version), or thunder and lightning had to be used (according to another) to rouse them. So in the 16th century, the Jewish mystics–who believed that every action of every individual affects the state of the world–developed an all-night vigil to compensate for the sleeping Israelites’ affront to God. A compilation of selections from Torah, Talmud, and Zohar, called Tikkun (improvement, or remedy) Leil ([for the] night [of]) Shavuot, was published for use on the holiday (although the learned often chose their own texts). Dark-to-dawn study on the first night of the holiday became customary.