None of the reasons for celebrating Lag Ba-Omer really make any sense to me. It is not the yahrzeit of Rabbi Shimon bar Yochai, nor do we normally celebrate yahrzeit’s with bonfires and rejoicing (and it is not mentioned in Chazal, Shulchan Aruch or any of the commentaries).
The Talmud (Yevamot 62b) says it is because the students of Rabbi Akiva stopped dying. But if you observe mourning in the first part of the Omer, the reason that they stopped dying must be because they were all dead. Not much cause for celebration (if you observe the second part of the Omer, presumably there were more about to die, just none died on the 33rd day of the Omer – still not a compelling reason for all the celebrations).
Chasam Sofer says it is the day that the manna began to fall in the desert. But that sounds like a reason made up after the fact, and also most people say that the manna began falling on Pesach Sheni.
It may also be connected somehow to the Bar Kochba rebellion. However I have not found any real source to support this theory, and it is all based on conjecture.
Rabbi Daniel Sperber in Why Jews Do What They Do: The History of Jewish Customs Throughout the Cycle of the Jewish Year
shows how many of the mourning practices are connected to the crusades.
The Chida says that the celebration is because that is when Rabbi Akiva began teaching Torah again to the five Rabbis in the south (after the death of the 24,000). That is a good reason.
I think the Arizal says (but if not, I’ll say it) that perhaps Lag ba-Omer is the day when Rabbi Akiva gave semicha to Rabbi Shimon bar Yochai (and Rabbi Meir). That would tie all the pieces together nicely.
Semicha began with Moshe giving Yehoshua ‘of his hod’ – the midah of 33 is hod she-be-hod.
The only problem (apart from no real basis for what I’m saying) is that it seems to be a matter of dispute between the Bavli and the Yerushalmi as to whether Rabbi Akiva gave semicha to Rashbi, or whether it was Rabbi Yehuda ben Bava.
In the Bavli (Avoda Zara 8b) it says:
אמר רב ברם זכור אותו האיש לטוב ורבי יהודה בן בבא שמו שאלמלא הוא נשתכחו דיני קנסות מישראל נשתכחו לגרסינהו אלא בטלו דיני קנסות מישראל שגזרה מלכות הרשעה <גזרה> {שמד} כל הסומך יהרג וכל הנסמך יהרג ועיר שסומכין בה תחרב ותחום שסומכין בו יעקר מה עשה רבי יהודה בן בבא הלך וישב בין שני הרים גדולים ובין שתי עיירות גדולות בין ב’ תחומי שבת בין אושא לשפרעם וסמך שם חמשה זקנים ר”מ ור’ יהודה ור’ יוסי ור”ש ורבי אלעזר בן שמוע ורב אויא מוסיף אף רבי נחמיה כיון שהכירו בהם אויבים אמר להם בני רוצו אמרו לו רבי ואתה מה תהא עליך אמר להם הריני מוטל לפניהם כאבן שאין לה הופכין אמרו לא זזו משם עד שנעצו לגופו ג’ מאות לולניאות של ברזל ועשאוהו לגופו ככברה
Verily that man, R. Judah b. Baba by name, be remembered for good, for were it not for him the laws of fine would have been forgotten in Israel? ‘Forgotten’! Surely, they could be studied? — Nay, they would have been abolished; for the wicked Government of Rome issued a decree that he who ordains a Rabbi shall be slain, likewise he who is ordained shall be put to death, the town in which an ordination takes place shall be destroyed and the tehum in which the ordination is held shall be laid waste. What did R. Judah b. Baba do? He went and sat down between two mountains and between two large towns between two tehums, namely, between Usha and Shefar’am and there he ordained five elders: R. Meir, R. Judah [b. Il’ai]. R. Jose, R. Simeon and R. Eleazar b. Shammua (R. Awia adds also R. Nehemiah). On seeing that they were detected by the enemies, he said to them, ‘Flee, my children!’ but they said to him, ‘And you, O Rabbi, what about you?’ ‘I,’ he replied. ‘will lie still before them, even as a stone that is not turned.’ It was stated that the Romans did not move from there until they drove three hundred iron spears into his body and made his corpse like a sieve!
However, in the Yerushalmi (Sanhedrin 6a-b) it says:
א”ר בא בראשונה היה כל אחד ואחד ממנה את תלמידיו כגון רבי יוחנן בן זכיי מינה את רבי ליעזר ואת רבי יהושע ורבי יהושע את רבי עקיבה ורבי עקיבה את רבי מאיר ואת ר”ש. אמר ישב רבי מאיר תחילה נתכרכמו פני ר’ שמעון אמר לו רבי עקיבה דייך שאני ובוראך מכירין כוחך.
Rabbi [Ab]Ba said: Originally ever person would appoint [give semicha to] his students. For example Rabbi Yochanan ben Zakkai appointed Rabbi [E]Liezer and Rabbi Yehoshua. Rabbi Yehoshua to Rabbi Akiva, and Rabbi Akiva to Rabbi Meir and Rabbi Shimon. It is said that Rabbi Meir sat down first. Rabbi Shimon’s face became upset. Rabbi Akiva said to him, “It is enough that I and your Creator recognise your strength.”
I’m not sure how to resolve the two, but according to the Yerushalmi it makes sense that Lag ba-Omer is the celebration of Rabbi Akiva and Rabbi Shimon bar Yochai.
Lag Sameach.
Here are some links to previous posts related to Lag Ba-Omer:
This is a source sheet on reasons for celebrating Lag ba-Omer. I’m sure there is an audio shiur to go with it somewhere, but I can’t find it. But I think it is fairly self-explanatory.
Since people seem to get excited by kabbalah on Lag Ba-Omer, here is my translation of the history of the transmission of kabbalah, which is translated from the introduction to Shomer Emunim Ha-Kadmon
Lag Ba-Omer (18th Iyar) may or may not be the yahrzeit of Rabbi Shimon bar Yochai, but it IS the yahrzeit of Rabbi Moshe Isserless (Rema):