Lag B’Omer means “the 33rd day of the (counting of the) Omer. This day is observed as a day of rejoycing because on this day, the students of Rabbi Akiva (who we discussed in # 20) did not die. We therefore are permitted to take haircuts, listen to music, hold weddings etc., because the signs of mourning which we have been observing are not necessary on this day of great happiness.
Lag B’Omer, the 18th day of Iyar, also corresponds to the date of the death of Rabbi Shimon bar Yochai, one of the great sages from the era of the Mishna. Although the death of a great sage is usually not marked with rejoycing, but rather with sadness, we treat Rabi Shimon bar Yochai differently. The Zohar in Parshas Ha’azinu tells us that on the day Rabbi Shimon passed away, a great light of endless joy filed the day, because of the secret wisdom he revealed to his students. That secret wisdom was written down and recorded in the holy Zohar. The happinesson that day was to him and his students like that of a groom while standing under the canopy at his wedding. On that day, the sun did not set until Rabbi Shimon had revealed all that he was permitted to. As soon as he was done, the sun set, and his soul returned to its Maker. Because of the happiness back then, we celebrate with happiness now, as well.
In Israel, people flock to the grave of Rabbi Shimon bar Yochai in the city of Meron. There is dancing, singing, bonfires are lit. Many people wait until their son is three before cutting his hair, and on the Lag B’omer of his third year, they cut the boy’s hair. There is also a custom that children play with bows (“keshet” in Hebrew) on Lag B’omer. A reason given for this is that in all the days of Rabbi Shimon bar Yochai’s life, a rainbow was never seen. A rainbow is a sign that the world was due for a flood of the proportion of that in Noach’s time. However, beacuse Hashem promised Noach that such a flood would never be brought again, Hashem lets us know when we are deservant of such punishment by placing a rainbow (“Keshet” in Hebrew) in the sky. In the merit of Rabbi Shimon, the world was never deservant of such punishment in his generation, and the appearance of a rainbow was never necessary. Therefore, children play with bows, which in Hebrew share the same word as rainbow.