If the Torah was carefully taught by Moshe to the Jewish people and was painstakingly passed from one generation to the next, how is it that we find so many differences of opinion among the Rabbinic Sages of the Mishnah and Gemara?
On today’s daf (=page) Rav Yehudah quotes Rav as teaching that during the period of mourning that followed Moshe’s death, 3,000 laws were forgotten. Although the Jewish people demanded of the prophets and priests that followed – Yehoshua, Shmu’el, Pinhas and Elazar – that they ask for Heavenly direction with regard to the questions that arose, each of them replies lo ba-shamyim he – “The Torah is not in Heaven” (see Devarim 30:12). Once the Torah was given at Mount Sinai it is incumbent on the Sages of every generation to establish the meaning of the Torah; whose meaning cannot be established by prophetic communication with God.
In explaining why so many laws were forgotten, the Gemara relates that just before his death, Moshe offered the opportunity to Yehoshua to ask him any question that he may have had. Yehoshua replied that he had not missed even a moment of service to Moshe (see Shemot 33:11) and therefore was certain that he knew everything. In consequence of this callous answer he was punished and forgot many laws.
The first recorded disagreement was the question of semikha. The Torah commands that the individual who brings a sacrifice to the Temple must place his hands on the animal’s head, between its horns, leaning on the animal with all of his strength. Should semikha be permitted on Yom Tov or not? In the Mishnah in Massekhet Hagigah (daf 16a), we find no fewer than five generations of Sages listed as arguing this point, which leads Rav Shemen bar Abba to quote Rabbi Yohanan as saying that even a shevut – Rabbinic ordinance – must be taken seriously. Semikha involves use of the animal (similar to riding a horse, for example) which is prohibited only on Rabbinic grounds, yet its status on Yom Tov is the topic of discussion for generations.