One of the most puzzling laws in Halacha (Jewish Law) is the requirement to observe a second day Yom Tov (festival) in all Jewish Communities outside the land of Israel.
Since in the olden days, when the Jewish calendar was not yet fixed to the extent it is today, there was a doubt concerning the day on which Yom Tov should be celebrated outside Israel.
The Sanhedrin, the Supreme High Court in Jerusalem, would declare a new month, after eye witnesses had brought evidence that they had just seen the new moon in its first appearance. Immediately, the court would declare this day the first day of the new month. Since this information would not always travel fast enough to Jewish communities outside the land, it became necessary for these communities to keep two consecutive days Yom Tov, depending as they were on the question, which day the new month had started in Israel. 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 date (as stated by the Torah), a two-day celebration became necessary.
This law is still applicable today. Consequently, any Jew living outside the land is required to observe two days such as on Pesach, Shavuoth and Succoth.
The difficulty with this rabbinical decree today, however, is that since the days of Hillel Hanasi (4th century, bc) an official and fixed calendar (not depending on eye witnesses) is in operation and, consequently, there is no longer any doubt which day is the correct day of Yom Tov. It is for this reason quite surprising why the Sages did not annul the second day Yom Tov, but insisted on its continuation.
The classical answer given is that since this had become the official minhag (custom) for so many years, it had become so well established, that an annulment would no longer be possible.
The famous Rabbi Naftali Zvi Yehuda Berlin, last Rosh Hayeshiva of the famous Volozhin Yeshiva, also known as Neziv (1817-1893) suggests in his Ha’emek Davar a completely different approach which to many will be an important eye opener.
In Parashat Emor (Vayikra 22), 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 do them, I am the Lord.” (v. 31) After offering an interesting approach to this problem, Neziv continues and states that the meaning of this verse is to instruct the Sages to make a fence around these festivals and to strengthen them by ordering a second day Yom Tov outside the land of Israel.
In his notes, called Harchev Davar, Neziv quotes a statement by the teshuvoth (reponsa) of Rabbi Hai Gaon, one of the greatest halachic authorities of the 10th century, which states that the requirement that one should keep a second day Yom Tov outside 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 [of Israel.]”
Neziv then comments that in principle there is absolutely no reason to keep a second day Yom Tov outside Israel even when one is not sure which day is the correct day (see above). His argument is that Jewish Law always follows the majority in all matters of halachic doubt, and since in most cases the Jewish months such as Adar and Elul have 29 days and not 30, there is no reason to keep a second day Yom Tov. After all, most of the time they consist of only 29 days.
Neziv continues and proves his point by stating that we would otherwise encounter a serious contradiction in Judaism. Why do we not keep two days Yom Kippur (the Day of Atonement)? And we could no doubt ask why, when counting the Omer outside Israel (49 days between Pesach and Shavuoth) we only count one date and not two? (After all, if Pesach would have started one day later, there should have been the need to start counting the Omer also one day later) In that case we should, for example, say (outside the land of Israel): “Today it is the 31st or the 32nd day of the Omer.” This is, however, not done and in fact forbidden.
Neziv therefore concludes that the above verse: “And you shall keep My commandments, and you shall do them” comes to teach us that we should be extremely careful to observe these festivals for two days and not to rely on the fact that most months have only 29 days and consequently keep them for only one day. The meaning of the verse then should 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 Neziv. Why should one observe two days Yom Tov outside Israel so as to make sure that we definitely celebrate them properly? 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 outside the land of Israel to get as inspired by a particular festival as when one lives inside the land of Israel. Israel carries its own spirituality into any festival, and in one day one is able to accomplish great spiritual achievements. Outside Israel, however, where the spiritual environment is not conducive to this kind of soul state, one needs two days to achieve the same goal. We may now understand why there is no requirement to observe two days for Yom Kippur. This is not only due to the fact that most 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 the same spiritual religious experience outside Israel as that of someone living in the land of israel. On this day the soul of a Jew should and could feel itself as if it dwells in the Holy Land and no second day is required. (2)
In that case we should attest to the fact that it is erroneous to argue in favor of a one day Yom Tov outside the land Israel. Modern interpretations of Judaism with their emphasis on greater spiritual quality, instead of condemning this institution should only welcome such a rabbinical enactment, since the quality of life in the Diaspora in modern times has (with all its beauty) definitely not been conducive to greater spiritual opportunities.
(1) For a short overview of this complicated issue see: Yom Tov Sheni Kehilchato by Rabbi Yerachmiel David Fried and The Book of our Heritage, first volume: Rosh Chodesh.
(2) 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 Israel there is no need for a second day, the Counting of the Omer would be no more spiritually uplifting if a second counting was added each time the mitzvah was done.