What is the real significance of Shavuot (literally "weeks") - the only festival in the Torah whose name does not define its essence? Unlike Pessah (Passover), which refers to the Paschal lamb whose blood protected the Israelite firstborn, and unlike Succot (Tabernacles), which refers to the booths in which the Israelites dwelt during their desert wanderings, Shavuot (known in English as Pentecost) refers to the weeks leading up to a specific day rather than to the day itself. Why? Fascinatingly enough, the precise date as well as the true meaning of this "mystery" festival involves a famous controversy between the Pharisees and the Sadducees - two groups which vied for ascendancy from circa 200 BCE to 200 CE. The Sadducees, who traced their origins to the priestly clan of Zadok and were committed to the plain meaning of the Bible (without the inclusion of many of our oral traditions), maintained that the command to count seven weeks "from the morrow of the Sabbath" (Lev.3:15) refers to the first Sunday after the onset of Pessah, from when Jews must begin counting seven complete weeks (from Sunday to Sunday), at the conclusion of which "you shall celebrate the Festival of Shavuot" (Deut. 16:10). These seven weeks fall during the first harvest period in Israel, beginning with the barley harvest (which is the initial omer sacrifice to be brought on that Saturday night) and culminating in the wheat harvest, expressed by the two loaves of wheat which is the central "first-fruit" gift of Shavuot. The Pharisees, forerunners of the Talmudic sages who endowed "last-word" authority to the Oral Tradition of biblical interpretation (perush), insisted that the biblical phrase "the morrow of the Sabbath" refers to the day following the first day of the Pessah festival (taking the Hebrew shabbat in this context to mean shabbaton, which is biblically used for "festival" elsewhere in that biblical passage). Obviously, the date for Shavuot would depend on when you begin your count. So divisive did this dispute prove to be - after all, the unity of the Jewish people is dependent on a common Hebrew calendar - that the day in which this controversy was settled (in accordance with the Pharisees) was itself declared to be a semi-festival on which one should neither fast nor recite a eulogy (B.T. Ta'anit 17b). What was the real significance of the debate? My revered teacher Rabbi Joseph B. Soloveitchik offered the following interpretation: According to the Sadducees, Shavuot is completely separate from Pessah, relating not at all to the Exodus but only to the agricultural reality of the Land of Israel; hence a unit of seven complete weeks - from Sunday to Sunday, beginning the first Sunday after the onset of Pessah only because Pessah also happens to fall in the harvest season - spans the barley to wheat harvests, a separate period of thanksgiving for an agricultural rather than an historical reason. From this perspective, Shavuot is a separate festival specifically celebrating the climax of the period with the wheat harvest, but logically incorporating within its name the entire seven-week harvest season, from barley to wheat. The Pharisees have a totally different interpretation. The very fact that the Oral Tradition insists that the count begin on the night following the first day of Pessah, which marks our historical exodus from Egypt - even if it falls in the middle of the week (as it usually does) - links the seven-week count inextricably to the historical meaning of Pessah. Moreover, for the Pharisees, Shavuot contains a historical as well as an agricultural significance; the Oral Law names Shavuot as the date when we received the Torah on Mount Sinai, the sixth day of Sivan - exactly 50 days after the 15th of Nisan, the first day of Pessah. Indeed, from the perspective of the Pharisees, Pessah is an incomplete festival, awaiting completion in the Festival of Shavuot. Pessah is merely our freedom from physical bondage, with our freedom from spiritual bondage (the internal blandishments of temptation and addiction) coming with the giving of the Torah on Shavuot; Pessah is "freedom from" which, unless properly channeled, can lead to reckless licentiousness; it is only the Torah which provides us with "freedom for." On Pessah we only get as far as the desert - an alien, hostile and undeveloped expanse, awaiting our entrance into Israel and the construction of our Holy Temple, which the Bible identifies with Shavuot, the festival of the first-fruits Temple sacrifice; Pessah is the first step, our festival of fate, when God took us out of Egypt with His "outstretched arm and strong hand," whereas Shavuot is our festival of destiny, when - by truly choosing to follow the dictates of Torah - we will lead the world to peace and redemption against the backdrop of Israel and Jerusalem (Isaiah 2, Micah 4). Hence, Shavuot is named Atzeret by the Pharisaic sages of the Talmud, which means "conclusion" - the days of the omer count serving as a connective period between the beginning of our freedom on Pessah and freedom's culmination in redemption on Shavuot. The progression from the one to the other demands rigorous introspection and repentance, commitment to our Torah and its ideals for world repair; the days of the counting of the Omer must be days of perseverance, preparation, penitence and purification. Therefore, the culminating festival of this period is known by the days of preparation, Shavuot; and, unlike Pessah and Succot, Shavuot doesn't have its own unique name because we have not yet reached the level of complete redemption. The last chapter of the Book of Ruth, which we read on Shavuot, takes place between the barley and wheat harvests, telling the story of a Moabite woman from whose womb will eventually come the king/redeemer. But this will only happen when we become truly worthy, because our sages tell us that the ultimate Redemption will require our repentance. Pessah and Succot celebrate what God did for us. Shavuot depends on our actions, and when these are found worthy, we will give the festival its name. The writer is the founder and chancellor of Ohr Torah Stone Colleges and Graduate Programs, and chief rabbi of Efrat.