Why we celebrate Lag Baomer/Did Rashbi pass away on Lag Baomer?
The recorded reasons for celebration:
The discussion in Poskim for why we rejoice on Lag Baomer: It is accustomed to increase slightly in joy on Lag BaOmer. For this reason, all Jewry omit Tachanun, and Ashkenazim even rescind the mourning customs on this day. The reason for this joy, however, remained a mystery and was the subject of discussion for many generations of Poskim. In search for an explanation behind this mysterious holiday, the Poskim offered various alternatives of events that happened on this day thus explaining why it is a day of celebration. Some Poskim, however, simply gave up there quest, stating that there is no satisfactory reason to defend the exorbitant joy expressed on Lag BaOmer, and thus in their eyes, the celebration of Lag Baomer remains a mystery. The following is a list of the classical reasons offered by the Poskim:
- The classical reason recorded in Poskim is that on this day, Lag BaOmer, the last of the 24,000 students died. This explanation, however, is not agreed upon by all opinions. Some Poskim hold that in truth the students of Rebbe Akiva did not stop dying on Lag BaOmer and hence the increase in joy is due to some other unknown reason.
- Others write the reason is because on this day Rebbe Akiva gave Semicha to Rashbi and his other four remaining students.
- Some write the reason for celebration is because on this day the Mun began to fall for the Jewish people in the desert.
- Others write it is because on this day we have reached the Sefira of Hod Shebehod, which contains mystical significance.
All the above however, even if accepted as true, only explains why we omit Tachanun on this day, it however does not explain the exorbitant joy expressed on Lag BaOmer, with the various customs associated with it, hence turning Lag BaOmer to a day almost equal to other Holidays.
The Kabalistic reason-Celebrating the day of Rashbi: Often in Jewish literature, when a sufficient explanation for a certain law or custom has not been uncovered we turn to the works of Kabbalah to perhaps uncover the mystery, and here is no different. The classical Sefarim of Kabbalah, which include the Shaar Hakavanos, Peri Eitz Chaim and Mishnas Chassidim state that on Lag Baomer one is to rejoice the joy of Rashbi. The Shaar Hakavanos and Peri Eitz Chaim, a work of Rav Chaim Vital based on the teachings of his famed master the Arizal, writes that people go to the grave of Rashbi on Lag Baomer to celebrate and that so was the custom of the Arizal. Rav Chaim Vital continues and adds that in fact the Arizal conveyed a message to one of his students from the Rashbi himself. What did Rashbi tell the Arizal to convey? He told him to ask his student “Why he said Nacheim on the day of his joy, and as a result of doing so he will soon enter into mourning.” Thus, we see that Lag Baomer is a day celebrating the joy of Rashbi, as quoted from Rashbi himself, and that everyone is meant to celebrate on this day and it is dangerous to ignore it. An additional source for this is also found in the Mishnas Chassidim, which is a major work of Kabalah written faithful to the teachings of the Arizal. There he states that on Lag BaOmer “It is a Mitzvah to celebrate the Simcha of Rashbi.” This reason which is sourced in Kabalah found its way into the classical works of the famed Posek, the Chida, who writes “And it is known that his desire is for us to celebrate on this day, as was revealed regarding the story with Rav Avraham Halevi.” It is likewise recorded in many later Achronim in their Halachic works as the reason for celebrating Lag Baomer. Thus, in conclusion, that which was clouded in mystery to the Poskim of earlier generations has become revealed to the later generations through the teachings of Kabala, that on Lag Baomer we celebrate because Rashbi himself instructed us to do so. The only question that remains is what is this joy all about? What happened to Rashbi on this day that he has instructed us to rejoice with him? This is what leads to our next discussion of did Rahsbi pass away on Lag Baomer.
Why Rashbi told us to celebrate: While the teachings of Kabalah uncovered for us the mystery behind the celebration on Lag Baomer, it has opened for us a new mystery regarding why Rashbi instructed us to celebrate. The Shaar Hakavanos and Mishnas Chassidim ibid write the reason one is to celebrate is because the Rashbi was one of the remaining students of Rebbe Akiva who was responsible for the continuity of the oral tradition of the Torah. The Shaar Hakavanos ibid explains based on Kabbalah why this celebration of the continuity of Rebbe Akliva and his teachings is connected specifically to Lag Baomer. Some suggest, as stated above, that Rashbi actually received Semicha on this day, and thus instructed us to celebrate. The most common explanation, however, is that this is the day that Rashbi passed away and he instructed us to celebrate on his Yom Hilula, the day of his passing. The only problem is, what is the source for this statement? The Shaar Hakavnos and Mishnas Chassidim, which are quite reputable sources, make no mention of it. So, in truth the answer lies in the Peri Eitz Chaim itself. Rav Chaim Vital in Peri Eitz Chaim ibid, writes in his conclusion of the above discussion [of Rashbi’s instruction to celebrate this day] “The reason that Rashbi died on Lag Baomer is because he was from the  known students of Rebbe Akiva who died on Lag Baomer.” Thus, a clear source from Rav Chaim Vital himself that this is the day of Rashbi’s passing. The only problem, however, is that this statement is blatantly inaccurate. It is clear from the Talmud and other sources that Rashbi was not part of the 24000 students who died in the plague and Rashbi passed away many years later. Thus, some Poskim conclude that this entire statement in the Peri Eitz Chaim must be a misprint, and so falls our source. Nonetheless, despite the above question on wording of the Peri Eitz Chaim, many Poskim record this tradition and write that Lag Baomer is the day of the passing of Rebbe Shimon. The earliest undisputed source is from the Alter Rebbe who writes in several Chassidic discourses of the passing of Rashbi on Lag Baomer, and discusses its celebration within his discourse. The Rebbe also concludes in his letters that this is the true reason for the celebration of Lag Baomer, as on this day Rebbe Shimon passed away. Furthermore, even the Divrei Nechmia who is one of the Poskim who questioned and invalidated the Nusach of the Peri Eitz Chaim concludes “Despite the invalidation of the source in Peri Eitz Chaim, certainly the concept is true that Rashbi passed away on Lag Baomer, as has already been publicized in the entire world for many generations the Hillula of the Rashbi on Lag BaOmer.” Last, but not least, in truth the wording of the Peri Eitz Chaim has been recently discovered to be authentic although with a slight change of wording. A careful study of the original manuscripts of the Peri Eitz Chaim found in multiple famed libraries [i.e. Oxford] show that although he did not write the above quoted wording which was questioned and invalidated by Poskim, he did write “The reason for Rashbi’s Simcha on Lag Baomer is because he was from the students of Rebbe Akiva, who is the one who died on Lag Baomer.” Thus, the last of the mysteries has been solved. Rashbi instructed us to celebrate on Lag Baomer because this is the day of his passing, as corroborated by the true manuscripts of Rav Chaim Vital, many Poskim, and the tradition of world Jewry.
Why the day of the Rashbi’s passing is a reason for celebration: A final and last step in the mysterious puzzle of the Lag Baomer celebration is understanding why the established reason of Rashbi passing away should be a source of joy or celebration. In fact, some Poskim who accept the tradition that this is the day of his passing, still question as why this should be a source of joy. The Rebbe suggests that since Rebbe Shimon requested that the day of his death be celebrated, it is thus a Mitzvah to fulfill the request of the deceased and celebrate on this day. Another reason brought down is that in truth the day of a Tzaddik’s passing is a great day of celebration above, as all the Tzaddik’s Torah and Avoda of his lifetime receives revelation on that day. This was stated by the Rashbi himself who coined the day of his Yartzite as a Yom Hilula. Alternatively, the day of the Rashbi’s passing a great treasure of the inner dimensions of Torah became revealed and thus we celebrate our access to his teachings in these later generations. Due to all the above, as writes the Alter Rebbe,“One is to rejoice with all his heart and soul and make a day of feasting and joy on the 18th of Iyar, and sing praise to Hashem from the book of Tehillim, however he is not to enter into drunkenness and frivolity, Heaven forbid.”
One is to celebrate and rejoice on Lag Baomer due to the various reasons mentioned above, of which the main reason is that on this day the Rashbi passed away and he instructed for us to celebrate on this day, to the effect that lack of celebration can bring negative consequences. The fact that Rashbi instructed us to celebrate on this day is undisputable in, and a careful research of the original manuscripts of the Peri Eitz Chaim show that the reason for this is due to the passing of Rashbi on this day, and so is accepted in the Poskim, amongst the Chabad Rabbeim, as well as the tradition of world Jewry.
Old manuscripts of Peri Eitz Chaim read as follows:
Manuscript from 1641
“וטעם שמח/ רשב”י ביום ל”ג לעומר כי הוא מתלמידי רבי עקיבא שהוא שמת ל”ג לעומר”.
“וטעם שמחת רשב”י ביו/ ל”ג בעומר כי הוא הי/ מתלמידי ר”ע והו/ שמת בל”ג בעומר”.
“וטעם שמ/ רשב”י ביום ל”ג לעומר כי הוא מתלמידי ר”ע שהוא שמ/ ל”ג לעומר”
 Admur 493:5; Rama 493:2; Maharil 157
 Admur 493:5; Siddur Admur; Rama 493:2
 Admur 493:5 [according to all opinions mentioned there]; Rama 493:2
Other opinions-Custom of Sefaradim: The above ruling is only in accordance to the ruling of the Rama ibid that the last of the students stopped dying on the 33rd day of the Omer. However according to the Michaber 493:2 the mourning custom fully apply up until the morning of the 34th day of the Omer as in his opinion the last of the students died on the 34th day of the Omer. This is the custom of the Sefaradim, and they hence do not get married or cut hair, or cease any of the mourning customs until the morning of the 34th day of the Omer. [Michaber 493:2; Peri Chadash 493:1; Mamar Mordechai 493:3; Kaf Hachaim 493:25; Yabia Omer 3:26; Minchas Yitzchak 4:84 that so is the Sefardi custom]
 See sources listed in coming footnotes, and Maaras Hayin of Chida in Likkutim; Shem Aryeh 14; Sdei Chemed Asifas Dinim 6
 P”M 493 M”Z 1; Peri Chadash 493:2; Chasam Sofer ibid
 Rama 493:2; Admur 493:5; Biur Halacha 493 “Yeish”
 Michaber 493:2 as explained in M”B 493:7; Tosafus brought in M”A 493:5; P”M 493 M”Z 1
 P”M 493 M”Z 1
 Implication of Shaar Hakavanos Shaar Sefiras Haomer p.87a, as explained in Kaf Hachaim 493:26; Chida in Maaras Ayin Likkutim 7:8, brought in Sdei Chemed and Kaf Hachaim ibid; See also Peri Chadash 493, brought in Kaf Hachaim 493:26
 These were Rebbe Yehuda, Rebbe Elazar Ben Shamua, Rebbe Meir and Rebbe Nechemia. On this day there was a special spiritual revelation which allowed these students to receive Semicha. [Shaar Hakavanos ibid, brought in Kaf Hachaim ibid]
 Chasam Sofer Y.D. 233; However, see also Chasam Sofer O.C. 163
 This follows the opinion of the Midrash, however according to the Gemara Shabbos 87b the Mun began falling on Shabbos the 15th of Iyar, and according to Tosafus there it began falling on Sunday the 9th of Iyar, which is before the 18th of Iyar. So is also apparent from Kiddushin 38a that the Mun lasted for 40 years minus 30 days, and the Mun ceased on the 16th of Nissan, hence proving it began falling before the 18th of Iyar. See Igros Kodesh 29:157
 Siddur Yaavetz, recorded in Chasam Sofer Y.D. 233
 So questions Peri Chadash 493:2; Chasam Sofer ibid
 Shaar Hakavanos Shaar Sefiras Haomer p.87a
 Peri Eitz Chaim Sefiras HaOmer 7
 See Ateres Zekeinim 493 that after bringing the story of Reb Avraham Halevi and the Arizal [recorded above] he concludes “We thus see one is not to say Tachanun on this day”
 Mishnas Chassidim Iyar 1:6
 Birkeiy Yosef 493:2 and Morah Bietzba 8:123
 Bnei Yissachar Mamar Lag BaOmer 3:3; Sdei Chemed Eretz Yisrael 6; Minchas Elazar 1:60; Divrei Nechemia 34-7; Chayeh Adam 131:11; Aruch Hashulchan 493:5; Kaf Hachaim 493:27
 See also Peri Chadash 493, brought in Kaf Hachaim 493:26
 Chida in Maaras Ayin Likkutim 7:8 and Kaf Hachaim 493:26 in tehri understanding of Shaar Hakavanos Shaar Sefiras Haomer p.87a
 Yevamos 62b
 See Divrei Nechemia 34-7
 Divrei Nechemia ibid; Chida in Maras Ayin Likkutim 7, recorded in Sdei Chemed ibid, however Cleary contradicting his earlier statement from Moreh Baetzba ibid
 Chida in Birkeiy Yosef 493:2 and Morah Bietzba 8:123 “Lag Baomer is the Yom Hilula of Rashbi, and it is known that his desire is for us to celebrate on this day, as was revealed regarding the story with Rav Avraham Halevi”; Chasam Sofer 233 “Lag Baomer Yoma Hilula Derashbi”; Bnei Yissachar Mamar Lag BaOmer 3:3; Sdei Chemed Eretz Yisrael 6; Minchas Elazar 1:60; Divrei Nechemia 34-7 “Despite the invaliudation of the source in Peri Eitz Chaim, certainly the concept is true that Rahsbo passed away on Lag Baomer, as has already been publicized in the entire world for many generations the Hillula of the Rashbi on Lag BaOmer.”; Chayeh Adam 131:11; Aruch Hashulchan 493:7 “It is customarily called Hilula Derashbi, and they say he passed away on this day and left the cave on this day”; Kaf Hachaim 493:27 accepts the version of Peri Eitz Chaim and says that both concepts are true
 Admur in Siddur Im Dach; Igros Kodesh Admur Hazaken p. 117 “The 18th of Iyar the Yom Hillula of the Rashbi”; Sefer Hamamarim 5564 p. 101 “To understand the Hillula of Rashbi”
 Igros Kodesh 4:275: “Many reasons have been recorded regarding the festival of Lag BaOmer. We only have the reason written in the Kisvei Arizal and brought in Dach that this day is the day of passing of Rashbi-the Yom Hilula of Rashbi”
 Divrei Nechemia 34-7
 See here for an analysis of the original manuscripts and the above stated conclusion http://www.shturem.net/index.php?section=news&id=62737
 Likkutei Sichos 3:1002; 32:256
 See Shach Y.D. 344:9 in name of Rav Yaakov Viyal [Mahariv]
 See Tanya Igeres Hakodesh 28
 See Zohar Vayechi p. 218a; Haazinu end of Idra Zuta p. 286; Divrei Nechemia ibid; Kaf Hachaim ibid
 See Divrei Nichemia bid
 Igros Kodesh Admur Hazaken p. 117;