Arutz Sheva Hebrew site, as every year, will stream live the "hillula" (memorial celebration) for Rabbi Shimon Bar Yochai direct from Miron. For details about the great Sage, see below.
Simeon bar Yochai, also known by his acronym Rashbi, was a famous 1st-century Tannaic (Mishnaic, ed.) sage in ancient Israel, active after the destruction of the Second Temple in 70 CE. He was one of the most eminent disciples of Rabbi Akiva, and is attributed with the authorship of the Zohar, the chief work of Kabbalah.
In addition, the important legal homilies called Sifre and Mekhilta are attributed to him. In the Mishnah, he is often referred to as simply "Rabbi Shimon." He is the fourth-most mentioned sage in the Mishnah.
According to popular legend, he and his son, Rabbi Eleazar b. Simeon were noted Kabbalists. Both figures are held in unique reverence by kabbalistic tradition. They were buried in the same tomb in Meron, Israel, which is visited by thousands year round.
According to the Talmud, Rabbi Shimon bar Yochai criticized the Roman government and was forced to go into hiding with his son for thirteen years. They sheltered in a cave (which local tradition places in Peki'in). Next to the mouth of the cave a carob tree sprang up and a spring of fresh water gushed forth. They studied the Torah all day long and left the cave when they received a Heavenly voice saying that the Roman Emperor had died.
Bar Yochai died on the 33rd day of the Omer, known as Lag BaOmer. On the day of his death, he revealed deep kabbalistic secrets which formed the basis of the Zohar. According to the "Bnei Yissaschar", on the day of his death, bar Yochai said, "Now it is my desire to reveal secrets... The day will not go to its place like any other, for this entire day stands within my domain..." Daylight was miraculously extended until he had completed his final teaching and died. As such, the custom of lighting fires on his yahrzeit (anniversary of death) symbolizes this revelation of powerful light.
His yahrzeit is widely known as a Yom Hillula, a day of celebration, there is thus a very widely observed custom to celebrate on his yahrzeit at his burial place in Meron. With bonfires, torches, song and feasting, the Yom Hillula is celebrated by hundreds of thousands of people. This celebration was a specific request by Rabbi Shimon bar Yochai of his students.
Some say, that as bar Yochai gave spiritual light to the world with the revelation of the Zohar, bonfires are lit to symbolize the impact of his teachings. As his passing left such a "light" behind, many candles and/or bonfires are lit here as well as in locales throughout Israel and the Diaspora.