Lag Ba'Omer and Counting the Omer The Bible (Leviticus 23:11) describes an offering consisting of an Omer (a sheaf of barley) that was brought to the Temple on the second day of Pesach. From that day onwards it was necessary to count 49 days until Shavuot, the Feast of the Wheat Harvest. After the destruction of the Temple, the practice of bringing barley was discontinued; however, the practice of "counting the Omer period" has continued throughout the ages. This counting period - or Sephirah - between Pesach to Shavuot is a period of semi-mourning, which has through the years become identified with sad memories for Jewry. Massacres occurred during the times of the Romans and later still during the Crusades. In the days of the Roman emperor Hadrian, the Jews led by Bar Kochba unsuccessfully attempted to drive out the foreign oppressors from Judea. During the fighting thousands of Jews died. Included were thousands of students of the saintly Rabbi Akiva who succumbed to a plague that raged during the Sephirah. Lag Ba'omer. According to some, the plague ceased on the 33rd day of the Omer (Lag Ba'omer). On this day, the ban from merrymaking is lifted. The day is also marked by many Chassidim as the day of departure from this world of Rabbi Shimon Bar Yochai, the father of Judaism's mystic tradition. Thus, on this date (18th Iyar) in Israel an all-night ceremony of bonfires and kabbalastic readings and prayers, takes place. Many children also have their first haircut on Lag Ba'omer.