One of the most infamous and perplexing aspects of Jewish practice is the notion of a second day of Yom Tov. This article aims to address the history of the practice and its relevance in modern times through classic Jewish texts.
The Gemara explains that before the Jewish calendar was fixed, the beginning of every Jewish month was declared by means of witnesses who would come to the Sanhedrin (Jewish court of law) originally based in Jerusalem and declare that they had seen the New Moon. After examination, if the witnesses were found to be telling the truth, the sages would declare the beginning of the month. This message was spread over the Land of Israel via a system of hilltop fires.
The difficulty arose with the fixing of the festivals. The Gemara records that messengers were sent from Jerusalem to the Diaspora in order to inform distant communities regarding the fixing of the festivals. Even though the Torah only stipulates that our festivals must be observed for one day, it became common practice for Jews in distant communities outside of the Land of Israel to observe two days of the festival. This was because it took more than two weeks for the message to arrive regarding the exact date of Rosh Chodesh making the calculation of the date of the festival very difficult.
If for example, Sukkot must be kept on the 15th of Tishrei there was insufficient time for the messengers from Jerusalem to reach Jewish communities more than two week’s travel away. In those far flung communities, Sukkot was therefore observed on both the 15th and 16th of Tishrei, whereas in the Land of Israel it would have only been observed on the 15th according to the Torah. Similarly, Rosh HaShannah which falls on the first of Tishrei would have to be observed for two days even in Israel. The reason was because in a case where the witnesses for the New Moon did not arrive until late on the 30th of the previous month of Elull, they would keep that day as the first day of Rosh HaShannah in case they arrived. If they did arrive, Elull would be 29 days and the 30th of Elull would become the 1st of Tishrei.
It is worth noting that while we can understand the need for communities to be strict in this case, there are also mitzvot (commandments) that those communities would lose out on by observing an extra day of Yom Tov. Since it is forbidden to wear Tefillin on Shabbat and Yom Tov, it would be impossible to perform that important positive mitzvah. Therefore, the addition of a second day of Yom Tov was not made lightly. Yet this strengthens the most fundamental question about the addition of a Second day of Yom Tov in modern times.
For over 1,600 years our calendar has not relied on witnesses to declare the onset of each new Jewish month. The change is largely attributed to Hillel II (not to be confused with Hillel who was a sage in Mishnaic times. Hillel II was the Nasi (leader) of the Sanhedrin between 320 and 385 CE.
In responsa of Rav Hai Gaon from the academy of Pumbedita during the early 11th century it appears that the calendar was fixed for a 19 year cycle of leap years in the year 358 CE. With it came the fixing of the Jewish months rendering the system of witnesses and messengers obsolete. Yet the practice of Diaspora communities keeping a second day Yom Tov continued even though the apparent reason for the practice no longer applied. The Gemara explains that:
.במנהג אבותיכם בידיכם זמנין דגזרו המלכות גזרה ואתי לאקלקולי
Give heed to the customs of your ancestors which have come down to you; for it might happen that the government might issue a decree and it will cause confusion [in ritual].
The Gemara above implies that we retain the tradition of second day Yom Tov in case governmental decrees prevent us from learning Torah, causing confusion in the calendar. While this is not unreasonable given the historical context of the Gemara, it appears practically inconceivable in the modern world. Maimonides explains that since there is no longer a Sanhedrin to uproot the practice of second day Yom Tov, even though according to the “simple law” it would be appropriate to keep only one day, Jewish law states that two days are kept in line with the Gemara.
Yet could the reasons given in the sources we have cited be only part of the picture, relevant for their time? Could we entertain the possibility that there other, perhaps deeper reasons for keeping a second day of Yom Tov outside the Land of Israel, beyond those already mentioned which appear obsolete?To begin to address this we must point to one glaring anomaly in the practice: the festival of Shavuot.
The Torah does not fix a date for Shavuot but simply commands us to count forty nine days starting from the second day of Pesach. This means that even before the calendar was fixed, the messengers had over two months from Rosh Chodesh Nissan before arriving in communities outside of Israel to declare the correct date of Rosh Chodesh. Long before the Shavuot, the messengers could have arrived and revealed the real date of Pesach meaning that the issue of doubt was no longer relevant; only one day of Shavuot needed to be kept.
Yet that was never the practice. Communities would keep two days Shavuot and this continues to be the custom today. There must therefore be some other reason, beyond the issue of doubt that led the Jewish people to adopt two days of Shavuot. If so, it may explain why we continue to keep two days Yom Tov for other festivals given that the calendar has been fixed.
To answer this we must examine the events surrounding Matan Torah (the giving of the Torah) which Shavuot commemorates and specifically piece together the exact date on which the Torah was given?
We know that in the year 2448, the Jewish people were commanded to take the Paschal offering on the 10th of Nissan. The Gemara records that the Jewish people slaughtered the Paschal offering four days later at the prescribed time (14th of Nissan). They left the next day on the 15th of Nissan which was a Thursday. This means that the 10th of Nissan was Shabbat which complements the notion that Shabbat HaGadol commemorates the taking of the Paschal lamb. We also know that when the Jewish people arrived at Sinai it was the 1st of Sivan.
Yet the big question is what happened next. The Gemara fills in some of the gaps left by the Torah. On Rosh Chodesh itself the people rest from the journey. On the 2nd and 3rd of Sivan God speaks to Moses declaring them a ‘Kingdom of Priests’ and setting up the boundaries around the mountain. God has commanded Moses and the people to prepare for two days and on the third day, God will reveal Himself and give the Torah. This process begins on the 4th of Sivan. This would lead us to the conclusion that the Torah was given on the 6th of Sivan, the date which we have fixed for Shavuot.
Yet there is one little Talmudic fly in the ointment; the same Gemara recounts a machlokes (disagreement) between the sages and Rebbi Yosi regarding the number of days that Moses actually directed the Jewish people to prepare. As we mentioned, God had told them to prepare for two days but according to Rebbi Yosi, with God’s agreement Moses added an extra day of preparation thus pushing off the giving of the Torah to the 7th of Sivan. One could try to dismiss Rebbi Yosi as a daas yachid (lone opinion), except that the Magen Avraham points out that we establish the halacha according to him. This means accordingly that the revelation on Mount Sinai actually happened on the 7th of Sivan.
Why then do we celebrate Shavuot on the 6th of Sivan? Moreover, we declare on both days that Shavuot is “Zman matan Torateinu” – the time of the giving of our Torah. In light of what we now know, the Magen Avraham asks how can we say this phrase on the first day?
The Bais HaLevi gives a fascinating answer. He begins by citing a famous aggadata which describes how the angels wanted to prevent Moses receiving the Torah. They felt Torah should stay in heaven. Moses argues with them pointing out that the majority of the laws relate to mankind and earthly activities, not to angels. Yet this seems obvious. Surely the angels would have realised that? Were they merely jealous of Moses for receiving these laws?
The Beis HaLevi explains that the angels were in fact less concerned about the written Torah, but instead wanted the oral aspect of Torah –the ability to expound the Torah and apply it in this world. That is why we say the phrase זמן מתן תורתנו –the time of the giving of our Torah. Our Torah refers to the oral Torah –the ability to expound Torah and this is precisely what Moses did when he reasoned that God’s command of preparing for two days was supposed to be for three days in total once you have considered the half day on the first day of preparation.
The two days of Yom Tovtherefore representboth the oral Torah (the 6th of Sivan when Moses made the first act of Oral Torah) and the written Torah (corresponding to the giving of the Written Torah on the 7th of Sivan). It is the Oral Torah that can truly be ours as the Talmudic dictum states, לא בשמים היא – the Torah is not in Heaven.
But if that is the case, why should the second day of Yom Tov only be practiced outside of Israel?
According to Rabbi Menachem Azariah of Fano since the Torah was given outside of the Land of Israel, God took the opportunity to give us our share in His Torah through the Oral Torah. He chose to celebrate Himself, in all His Glory, the second day of the Diaspora holiday which Moshe added on his own initiative according to Rebbi Yosi.
According to this, since the Torah was given outside the land of Israel, when Moshe added one day with God’s approval, God was also approving the extra day of Yom Tov that Moses had created. This explains why Shavuot has a second day Yom Tov and indeed is the paradigm second day Yom Tov and source for all of the other second day Yom Tovim. This is also the reason why even though the basis given by the Rambam for second day Yom Tov is no longer valid as our calendar is fixed, each second day Yom Tov has its source in this seminal moment of Moses adding one day.
Let us thank God for this wonderful opportunity to celebrate and enjoy two days of Yom Tov and inspire ourselves of its true source: the nature of Torah itself. We have both an Oral and Written Torah. While we often prioritise the Written Torah as God’s Divine Will, in His infinite wisdom He declared that we too should have our own share in Torah, the Oral Torah which continues to this very day.
 Babylonian Talmud Rosh HaShannah 23b (see Mishnah there)
 Babylonian Talmud Rosh HaShannah 22b (see Mishnah there)
 Babylonian Talmud Tractate Rosh HaShannah 18a
 Numbers 29:12
 Rambam, Mishnah Torah Laws of Sanctification of the Month, Chapter 5 Halacha 4
 Even when witnesses were relied on, it is clear that communities understood that each of our months were designed to last for either 29 or 30 days and that they knew which months should be 29 and which should be 30. It is worth noting from this case that the primary day of Rosh HaShannah is in fact the second day and the day added out of doubt is the first day (see Babylonian Talmud Beitzah 4b and Rashi, ibid. ד”ה כל היום.
 Babylonian Talmud Tractate Beitzah 4b
 Mishnah Torah, Sanctification of the Month, Chapter 5 Halacha 5
 Exodus 12:3
 Babylonian Talmud Tractate Shabbat 87b)
 Shulchan Aruch Orach Chaim 430:1 and Mishnah Berurah 430:1.
 Exodus 19:1 see Rashi ibid.
 Babylonian Talmud Tractate Shabbat 86b – 87a
 Exodus 19:6
 Exodus 19:12
 Exodus 19:10
 Rabbi Avraham Gombiner, Magen Avraham on Orach Chayim Siman 494 (Introduction)
 Babylonian Talmud Tractate Shabbat 88b – 89a
 See the Gemara in Shabbat 88b-89a for a detailed account of the drasha that Moses made from God’s command.
 See Deuteronomy 30:12 and Babylonian Talmud Tractate Bava Metzia 59b
 Sefer Asarah Ma’amaros, Ma’amar Chikur Hadin 2:15