The Mishnah marks the culmination of the transition from Prophetic Judaism to Rabbinic Judaism. The period before that – from the time of Ezra to the establishment of the Anshei Knesset Hagedolah (Men of the Great Assembly) – is the tipping point which takes us there. The sages themselves believed that the age of prophecy had run its course with the end of the Babylonian exile, and that prophecy was not longer the means of Divine revelation or discourse. More importantly, they saw in themselves the direct spiritual descendants of that chain of ‘kabbalah’ linking them to God’s revelation at Sinai.
In the books of Nevi’im (Prophets) , we see how the navi (prophet) acted at times as a domestic adviser gifted with the power of divine knowledge (Shmuel helping Shaul – Saul – find his father’s donkeys) and at times as a religious leader (Shmuel, again, quoting the book of Devarim – Deuteronomy – on the rules governing a king) . To the sages, these dual roles were suited to the navi as a personality spiritually attuned to God and a scholar, conversant with Torah – the laws – and capable of adapting it to his (or her) time through Takkanot – adjustments.
“Moshe received the Law from Sinai” is much more to the point than the elaboration in Avot d’Rabbi Natan. Simply stated: Moshe was there to get the law. He received it (from God) and proceeded to teach it to his students, beginning the chain of transmission from God to the generation of the Mishnah.
Once we accept this ‘evolution’ this as historic fact, we can then begin to understand what the Mishnah is and the tradition it reflects. The tradition is the conclusion of generations of accumulated takkanot which appear in the Mishnah as binding laws from early on (Torah she’be’eal peh) but which had no mention in the Torah she’bikhtav. Some were given to Moshe which he transmitted to Yehoshua. Some were innovations Yehoshua himself added. Others came from later prophets and leaders. All were part of the oral tradition ‘halakhah le’Moshe mi’Sinai ‘– laws given to Moshe from Sinai – that is, inferred from the written law by rules passed down from Moshe to his disciples. This is what the Rambam – Maimonides refers to when he writes the history of transmission of Torah from generation to generation. (See attachment)
It’s the ‘hardware’ (the text) & the ‘programs’ (mitzvoth) and the ‘software’ (how to program the Torah to adapt it to successive generations) that goes from Sinai in a direct line to the time of the Mishnah, and ultimately our time.
The sages said the first generation of takkanot came when the Jews invaded and settled Canaan. Some takkanot they attribute to Yehoshua deal with civil and social law, adapting the Torah written in outline form for a Bedouin society to a new ‘urban’ reality. These are logical inferences. Other “Yehoshu-ic” traditions of a religious nature, or religious traditions attributed to other figures in Nevi’im, are harder to prove, though some are explict, like Ezra’s takkanah to read Torah during the week. Additional post-biblical adaptations are attributed to the Anshei Knesset Hagedolah, whose role was to create a post-prophetic Judaism which would unify Judaism for the Judean and Diaspora communities.
Legends and stories from the midrash and other sources back the sages’ interpretation of history. They also show that the sages had an almost scientific understanding of Torah she’be’eal peh’s evolution. The Torah she’bikhtav is the starting point for us as a nation and it is also the starting point of other traditions and beliefs. It was (and is!) Torah she’be’eal peh which distinguished us from the others because it preserves the spiritual essence of what was written and goes beyond it, creating a common culture and way of life that brings us together no matter how far apart we are.