One of the most puzzling laws in Halacha (Jewish law) is the requirement to observe a second Yom Tov (festival day) in all Jewish communities outside of Israel.

Before the establishment of a set calendar for the Jewish year, there was doubt concerning the day on which a Yom Tov should be celebrated outside of Israel.

The highest Jewish court, the Sanhedrin in Jerusalem, would declare the first day of a new month on the basis of eyewitness testimony given by people who had just seen the first appearance of a new moon. The court would then immediately send out messengers to inform nearby communities which day was declared to be Rosh Chodesh (first day of the month) so that they could observe the festivals at the proper time.

Jewish communities located outside the land of Israel or too far from Jerusalem to be informed of the precise day of Rosh Chodesh, were told to keep two consecutive Yom Tovs, since they could not know on precisely which day the new month had started in Israel.

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Since a Jewish month can consist of 29 or 30 days, there could be a difference of one day. And since Biblical festivals always have a fixed and specific date in the month (as stated by the Torah), a two-day celebration became necessary.

This law is still applicable today. Consequently, any Jew living outside of Israel is required to observe two days of Pesach, Shavuot, and Sukkot.

The modern difficulty with this rabbinical decree is that since the days of Hillel HaNasi (4th century CE), an official and fixed calendar independent of eyewitnesses is in operation and, consequently, there is no longer any doubt about which day is the correct day for a Yom Tov. It is therefore quite surprising that the sages did not annul the observance of a second Yom Tov, but insisted on its continuation.

The classical reason given is that since this had become the official minhag (custom) for so many years, and was so well established, an annulment would no longer be possible.

The renowned Rabbi Naftali Tzvi Yehuda Berlin — also known as Netziv (1817-1893) — the last head of the famous Volozhin Yeshiva, suggests a completely different approach in his Ha’amek Davar, which will be an important eye-opener to many.

In Parashat Emor (Vayikra 22:31), we are introduced to the festivals of the Jewish year with the following seemingly superfluous words: “And you shall keep My commandments and you shall perform them. I am the Lord.”

After offering an interesting approach to this problem, Netziv states that the reason for this “superfluous” verse is to instruct the sages to make a fence around these festivals and strengthen them by requiring a second Yom Tov outside the land of Israel.

In his notes, called Harchev Davar, Netziv quotes a statement in the teshuvot (responsa) of Rabbi Hai Gaon — one of the greatest halachic authorities of the 10th century — in which he says that the requirement of keeping a second Yom Tov outside of Israel was already alluded to by the prophets. He concludes with the following words, “And perhaps this was done since the days of Yehoshua ben Nun (Joshua) for those who lived outside [the land of Israel].”

Netziv then comments that in principle there is absolutely no reason to keep a second Yom Tov outside of Israel, even when one is not sure of which day is the correct one. His argument is that Jewish law always follows the majority in all matters of halachic doubt, and since in most cases the Jewish months have 29 days and not 30, there is no reason to keep a second Yom Tov.

Netziv continues and proves this point by stating that we would otherwise encounter a serious contradiction in Judaism. Why don’t we keep two days of Yom Kippur? And we could no doubt ask why when counting the Omer (the 49 days between Pesach and Shavuot) outside of Israel, we only count one date and not two. After all, if Pesach started one day later, the Omer would have to begin one day later as well. In that case we should, for example, say outside of Israel, “Today is the 31st or the 32nd day of the Omer.” This, however, is not done and is in fact forbidden.

Netziv therefore concludes that the verse, “And you shall keep My commandments, and you shall perform them” teaches us that we should be extremely careful to observe these festivals for two days. We should not rely on the fact that most months have only 29 days and consequently keep the festivals for only one day. The meaning of the verse then would be: And you shall surely keep them in the best way possible and not allow for any doubt.

We may wonder, however, to what specific matter our verse is alluding, according to Netziv. Why should one observe two Yom Tovs outside of Israel so as to make sure that we definitely celebrate them properly? Why not follow the majority of months with only 29 days?

The answer may be found in an observation made by Rabbi Menachem Recanati, one of the great kabbalists of the 13th-14th century. He tells us that it is impossible for people outside the land of Israel to be as inspired by a particular festival as it is for people inside the land of Israel. Israel carries its own spirituality into any festival, and in only one day, people are able to make great spiritual achievements.

Outside of Israel, however, where the spiritual environment is not conducive to such inspiration, one needs two days to achieve the same goal. We may now understand why there is no requirement to observe two days of Yom Kippur. This is not only due to the fact that people will not be able to fast for such a long time, but also because Yom Kippur, due to its extraordinary nature, is able to offer us the opportunity to achieve almost the same religious experience outside of Israel as that of someone living inside it.

On this day, the soul of a Jew could and should feel as if it dwells in the Holy Land and no second day is required. (The reverse is true regarding the counting of the Omer. While Yom Kippur is able to offer us great spirituality, even to the point that outside of Israel there’s no need for a second day, the counting of the Omer would be no more spiritually uplifting if a second counting were added each time the mitzvah was done.)

In that case, we should state that it is erroneous to argue in favor of a one-day Yom Tov outside of Israel. Modern interpretations of Judaism, with their emphasis on greater spirituality, should only welcome such a rabbinical enactment instead of condemning it, since the quality of life in the modern-day Diaspora (even with all of its beauty) has definitely not been conducive to greater spiritual opportunities.

As anyone can testify, celebrating the Jewish festivals in Israel is an act of supreme delight. The festivals are invested with a very special spirit that cannot be experienced anywhere else.

No other land can compete with the land of Israel!

This, it seems, is the secret behind the second Yom Tov and why the sages did not abolish it.

Rabbi Dr. Nathan Lopes Cardozo is the Founder and Dean of the David Cardozo Academy, as well as the author of 13 books and numerous articles in both English and Hebrew. Hailing from the Netherlands, Rabbi Cardozo is known for his original and often fearlessly controversial insights into Judaism.