This coming Saturday night, the holiday of Shavuot will be celebrated by Jews all over the world, but this holiday, more than any other Jewish festival, is celebrated differently by different communities in different places.In fact, this holiday probably has more names than any other festival. Also known as Hag Hakatzir (Harvest Festival), Hag Habikurim (Festival of the Firstfruits) and Hag Matan Torah (Festival of the Giving of the Torah), it is most commonly known today as Shavuot (Festival of Weeks), indicating a strong connection to the days we count from Passover.We mark the time between our liberation from Egypt to the day we received the Torah at Mount Sinai, although in the Torah itself the only counting mentioned is a function of the agricultural calendar, instituted after the Israelites entered the Land.In many communities, people will gather after the festive evening meal to celebrate the giving of the Torah. Practices vary; some communities will recite the traditional “tikun,” a prayer generally associated with Sephardi and Kabbalistic custom, while others will convene learning sessions, host lectures or conduct discussion groups.In Jerusalem, the uplifting intellectual and religious experience culminates in a unique, oncea- year, spiritual and experiential climax, as many thousands of people march through the dark streets toward the Old City, where tens of thousands participate in the holiday morning prayers as the sun rises over the Western Wall.These nocturnal practices are not mentioned in the Torah or even in mainstream rabbinic literature.In fact, the Torah does not clearly identify Shavuot, 6 Sivan, as the day on which the Torah was given. The Torah identifies this date as an agricultural holiday, the day the eponymous bikurim are brought to the Temple in Jerusalem, and a type of thanksgiving celebration is held. To be sure, this ceremony is not limited to this particular day; rather, on Hag Habikurim one may begin to bring the firstfruits, a process that continues through Hanukka, as different species come into season.While the Torah does not specify the date the Torah was given, reading the biblical narrative leads us to the conclusion that the great revelation at Sinai occurred more or less at the same date assigned to Hag Habikurim. According to the dominant tradition, 6 Sivan was the precise day that the Jewish people received the Torah at Sinai; the holiday of Matan Torah and the festival of Shavuot/Bikurim share the same date on the calendar.A notable exception to this view is the Magen Avraham (Rabbi Abraham Abele Gombiner), who concluded that the Torah must have been given on the following day, 7 Sivan. This, to his mind, reinforced the significance of the celebration of the “second day of galuyot,” the additional day observed by those residing outside Israel.The custom of staying up all night – often called Tikun Leil Shavuot, can be traced back to the Zohar, which describes the “Tikun” not as “fixing” something but in the sense of “making ready,” as one would prepare a bride for her wedding. The Zohar understood that the events at Mount Sinai were akin to a wedding between God and the Jewish people.Another tradition regarding Tikun Leil Shavuot was popularized by the kabbalists of Safed. Despite the significance of that singular occurrence on 6 Sivan, the awesome theophany and the greatest revelation ever to have been experienced by mankind, the events of that first Hag Shavuot were tainted.The Midrash tells us that some people overslept on the day the Torah was to be given, and God had to awaken them from their slumber with thunder and lightning.For this reason, there are those who stay up all night – to “repair” or make amends for that ancient mistake. (We might note that this custom is relatively recent; it has been observed that some of the success of this nocturnal custom may be attributed to the concurrent introduction and availability of coffee.) As Jews returned to the Land of Israel in the 19th and 20th centuries, the agricultural aspect of the holiday resonated with the halutzim, both religious and secular. This expression of joy and thanksgiving for the firstfruits struck a chord with those who worked the land as well as those who had long dreamed of living off its bounty.On the other hand, Diaspora Jews often seem oblivious to the agricultural aspect of the holiday. A favorite sermon that seems to circulate in Diaspora synagogues every year revolves around the curious “fact” that in contradistinction to Passover and Succot, Shavuot is not associated with any mitzvot, leaving the receiving of the Torah, and Torah study in a more general sense, the de facto identity of the day. Rabbis and students wax on with great enthusiasm that the significance of Shavuot and the source of its holiness is Torah alone, completely forgetting the Torah-mandated offering and ritual of the firstfruits. Another widespread custom practiced in most Ashkenazi communities on Shavuot is to read the Book of Ruth. At first glance, the rationale for this custom lies in the fact that Ruth is the prototypical convert to Judaism. Just as she accepted the Torah and tied her destiny to the Jewish people, so, too, all those who accepted the Torah at Sinai “converted” to Judaism.While this is certainly so, we should note the larger context and contours of the megila. The Book of Ruth is the perfect text for Shavuot because it merges the two themes – we might say, the two identities – of the holiday: accepting the Torah and rejoicing in the bikurim. The agrarian society in the Land of Israel is the backdrop of the story. The major events in the narrative take place at this particular time of year, as the first wheat harvest is under way.Every Passover, in one of the most joyous moments of the Seder, we sing, “Had God brought us to the foot of Mount Sinai and not given us the Torah – dayenu,” it would have sufficed. How can this be? What other purpose could our trip through the desert to some heretofore unknown mountain possibly have had? The answer lies in a well-known rabbinic teaching cited by Rashi in his commentary to Exodus 19:2.On their path through the desert to the Promised Land, the Israelite camp was often a place of division and strife, but at Mount Sinai something magical happened: We became a unified people. We became one, “like one person, with one heart.”We might say that this brings us full circle: The Six Day War of 1967 changed the city of Jerusalem, returning it to Jewish sovereignty for the first time in millennia. In the days after the war, the Old City and the Western Wall were closed off; there were mines to be cleared and structures to be secured. The first time the Wall was opened to the public was on the morning of Shavuot in 1967.An acquaintance of mine who was among the crowd that day told me that it seemed as if the entire Jewish people was there, either in person or through a representative. Religious and nonreligious people walked through the streets and made their way together to the Western Wall, as if in a dream. These Jews, so varied in outward appearance and outlook, were totally united as they celebrated the holiday of Shavuot as it had not been celebrated for 2,000 years.Perhaps some of them had Torah on their minds, while others thought about the Land of Israel; some may have focused on the physical, and others on the ethereal. But they were united – as one person, with one heart.That is the truest celebration of Shavuot, and the way we should strive to celebrate it every year: with complete unity.