Lag B'Omer, the 33rd day of the Omer count—this year, May 14th 2017—is a festive day on the Jewish calendar. It is celebrated with outings (on which the children traditionally play with bows and arrows), bonfires, and other joyous events. Many visit the resting place (in Meron, northern Israel) of the great sage and mystic Rabbi Shimon bar Yochai, the anniversary of whose passing is on this day.
Rabbi Shimon bar Yochai, who lived in the second century of the common era, was the first to publicly teach the mystical dimension of the Torah known as the “Kabbalah,” and is the author of the basic work of Kabbalah, the Zohar. On the day of his passing, Rabbi Shimon instructed his disciples to mark the date as “the day of my joy.”