See also
http://ohr.edu/yhiy/article.php/1438
G-d gave the Torah to Moses and the Jewish people at Mount Sinai 3,316 years ago. This was seven weeks after the Exodus from Egypt, on the 6th day of the month Sivan, in the year 2448 of the Jewish calendar. On that day, G-d revealed Himself to the entire Jewish people (which included some 600,000 adult men, in addition to women, children and the aged) and declared to them the Ten Commandments. Afterwards, Moses ascended Mount Sinai where, for forty days, G-d taught him the entire Written and Oral Torah. Later, on Yom Kippur, Moses descended with the second tablets of the Ten Commandments and began to teach the people what he heard from G-d on Mount Sinai.
This was the only event in history where G-d revealed Himself to an entire people, who simultaneously witnessed and experienced His will. "And G-d said to Moses, I come to you in a thick cloud, so that the people may hear when I speak with you" (Ex. 19:9). "And Moses brought forth the people out of the camp to meet G-d, and they stood at the bottom of the mount" (19:17). "And G-d spoke all these words saying, I am the Lord your G-d" (20:1). "And all the people perceived the thundering, and the lightning, and the voice of the horn, and the mountain smoking" (20:15). Moses himself emphasized to the people the uniqueness of this event: "Did ever a people hear the voice of G-d speaking out of the midst of the fire, as you have heard? To you it was shown that you might know that the Lord is G-d" (Deut. 4:32-35).
Rabbi Joseph Albo (Spain, c. 1400) comments on the significance of the way in which G-d gave the Torah: "That which is perceived by the greatest number of people is most widely believed; therefore the Holy One wanted the Torah to be bestowed through Moses with the greatest possible publicity and before a multitude of more than six hundred thousand…comprised of intelligent and astute men of diverse characters and attitudes so as to leave not the slightest shadow of a doubt in the minds of its recipients or in the minds of subsequent generations. Thus its reception would be both as correct and as fully credited as possible".
The Written Torah is the word of G-d that He dictated to Moses word for word, and which Moses wrote in the first Torah scroll. It incorporates all the commandments, including the Ten Commandments. It is called the Written Torah because it was to be passed throughout the generations in written form, each Torah a copy of a previous one such that all Torah scrolls are identical to that written by Moses. The Oral Torah, which was also given to Moses at Sinai, is the explanation of the commandments of the Written Torah, and was to be passed down through the generations in an unbroken oral transmission. Eventually the Oral Torah was compiled in written form in the Mishna and Talmud.
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