What is the Oral Torah? Is it a part of the Torah, a commentary, a rabbinical addition, or something else?
In order to properly understand what the Oral Torah is and its relation to the Written Torah, it’s important to first say a few words about the Written Torah.
G‑d gave the Torah to the Jews at Mount Sinai in approximately 1300 BCE entirely orally with nothing being written down other than G‑d’s inscribing the Ten Commandments on the Tablets. From the base of the Mount, the Jews heard and experienced G‑d’s oral transmission of the Ten Commandments, and later witnessed from afar for forty days the wondrous occurrences that accompanied G‑d’s giving the rest of the Torah, also orally, to Moses at the top of the Mount.
During those forty days, G‑d taught Moses everything humanly possible to understand about the Torah, which included the deepest and most detailed teachings of belief, law, practice, ethics, and any other field needed to understand, apply and fulfill the Torah. Afterward, during the forty-year sojourn in the wilderness, G‑d dictated to Moses what parts of the vast amount of oral knowledge that Moses received at Sinai should be written and how. G‑d also dictated to Moses what and how to record the events that took place during that sojourn. This culminated in the Written Torah, or what is also referred to as the Five Books of Moses.
The rest of the knowledge that G‑d gave to Moses at Sinai which had not been written down in the Torah remained oral, and was taught by Moses to the People orally, and thereby became the basis for what is referred to as the Oral Torah, which was eventually written down approximately 1500 years after Sinai, in the form of the Talmud.
Thus, while the part of the knowledge of Sinai which G‑d dictated to Moses was written only in general, outline form, the Oral Torah contained and preserved all the depth and detail of the knowledge that G‑d taught to Moses during the entire forty days atop the Mount. In this way, the Oral Torah complements the Written Torah, and the two are inextricably bound as One Torah. In fact, it is impossible to understand or practice the teachings of the Written Torah without the parallel explanations of the Oral Torah.
One example of this regards the mitzvah of tefillin, although the dynamic applies to absolutely every idea or law of the Torah. Basically, all the Torah says about tefillin is “you shall bind these words on your arm and they shall be a sign between your eyes”. From these words alone, the mitzvah is a “non-starter”. What words, how shall they be written, with what, on what; in what, what material, size, shape and color; how shall they be bound, with what, what shape and color; exactly where shall they be bound, by whom and when? These are just some of the questions which preclude performing the mitzvah on the basis of the Written Torah alone. How could G‑d command us to “do” or “don’t” without detailing the parameters of the mitzvah? Where did G‑d reveal all this mandatory information?
The answer is: In the Oral Torah.
But the Oral Torah is not just an explanation of Torah Laws. It also explains the manifold meanings of Torah verses, including the explanation of ambiguous or cryptic passages, and is also replete with esoteric teachings. So in truth, the Written Torah cannot really be understood on any level without the G‑d given supplemental Oral Torah.
And even though the Oral Torah was eventually recorded in writing by the Talmudic Sages – first in the Mishna and later in the Gemora, together comprising the Talmud – the essential core of what we refer to now as the Oral Torah in the Talmud is not rabbinic in origin. Rather it is the relatively well-preserved version of the Oral Torah initially received by Moses and transmitted orally from generation to generation until it was written down in Talmudic times.
That being said, insofar as the Torah grants authority to rabbis of the caliber of the Talmudic Sages to enact rabbinic legislation, the Talmud also includes all of the non-Torah, specifically rabbinic laws, customs and teachings which were added to Judaism by such Sages throughout the generations. However, the Sages were meticulous in distinguishing between the original core teachings of the Oral Torah and their additional teachings which were also recorded in the Talmud. Thus, it is very clear in the Talmud what teachings originate from Sinai, and which are Rabbinic.
In addition, not only did the Sages add their teachings alongside the core Sinai Oral Torah, but they also included in the Talmud fascinating, brilliant, and timeless observations and insights on many topics which became part of the general body of Jewish knowledge which accrued over the generations, including History, Natural Science, Culture, Comparative Religion, Ethics, Philosophy, Music, Mathematics and much more.