I have written several times in the past about the centrality of Deuteronomy 17:5-13, which is the very foundation of the Oral Torah and rabbinic authority. When there is a question of how to follow a Torah command, we are to turn to the sages, priests and prophets who formed a central court, later known as the Sanhedrin. We are commanded to follow their teachings, instructions and enactments. With the demise of the Sanhedrin in the fourth century CE, rabbinic authority remains, albeit in a limited form. According to RASHI and most Ashkenazic authorities, the power of the Oral Torah shifted to all the Torah Greats in a generation, who, in a sense, form a kind of Sanhedrin. According to RAMBAM, followed by most Sepharadic opinion, rabbinic authority only extends to a community's rabbi, with no powers beyond his own community. In any case, the Torah is not for individual interpretation of practices, but comes with instructions! Without the Sages, the Written Torah is a closed book.
A fascinating part of the Oral Torah is known as an "Asmachta" (Aramaic for "leaning"). The Torah empowers the sages to enact legislation to protect the Torah ("fences around the Torah"), without adding to the number of Biblical laws. Sometimes, the sages would "lean" a purely rabbinic law on a Biblical text. For instance, the Torah commands us to tie the Tefillin on our arm and head. But which arm? The rabbis had received a clear tradition that it was the left arm (for lefties, most agree that they are to put the tefillin on the right arm). This was always part of the Oral Torah. But the Talmud, the central work of the Oral Torah, says that, in fact, there is a Biblical reference to this idea. Of the four places where the Torah commands Tefillin, in one place, the word "Yadecha" (your hand/arm) has an unusual spelling, so that it can also be read "weaker arm". Now, no one would argue that this is the literal meaning of the verse. Rather, the idea has been "leaned" onto the verse for support. Here, we have two interpretations. One view is that the asmachta was simply a device used to give SOME Biblical authority to a rabbinic enactment. Another, far more accepted view, is that, in fact, the Torah has not as yet revealed all her secrets. The Torah is wider than the seas, vaster than the Heavens. Besides the laws clearly given in the Torah, or handed down by oral tradition, the Torah contains infinite "hints". Some may be universal, some may apply to a given time, place or situation. Some may even be individual. Some great Tzaddikim, when asked a question, may open a Torah text at random, and find the answer there! (I have seen this with my own eyes). Therefore, "minor" variations in spelling, grammar or syntax can actually be hints to sages of future generations as to how to act in a given situation. The unusual spelling of "Yadecha" was put there by G-d Himself, to guide the sages should a question arise. Over the last seventy years, many rabbis have discovered messages in the Torah that were previously unknown, by certain letters occurring at certain intervals (every twenty fifth letter, for example) which spell out a clear message.
The rabbis tell us that the Torah existed for two thousand years before the world was created. Although there are many interpretations of this idea, one thing is certain. I, you, every man, woman and child who ever lived or will live is in the Torah. The Sages can see this, and guide us accordingly. We must be aware that the Torah is not just a book. The Zohar states that the first word in the Ten Commandments (Anochi/I am) is an acrostic of "ana nashi ketavit yehavit" (I wrote and gave you My Self). When we touch the Torah, we touch G-d. But we need to learn from those who know, how to see this and make it into a reality in our lives.