|The Study of halakhah in the rabbinic period and
beyond it became the supreme religious duty. Because of
it's difficult subject matter and it's importance for
practical Judaism this study took precedence over that of
any other aspect of Jewish teaching. typical is the
rabbinic saying that after the destruction of the temple,
God has nothing else in His world than the four cubits of
the halakhic study over aggadic was expressed in the
parable of the two merchants, one selling precious
stones, the other small ware. Only the connoisseur comes
to buy from the former (Sot. 40A).
The general assumption in the classical Jewish sources is that the halakhah in it's entirety goes back to Moses, except for various later elaborations, extensions, applications, and innovations in accordance with new circumstances.
This Maimonide (yad, intro) counts 40 generations backward from R. AShi, the traditional editor of the Babylonian Talmud, to Moses and he concludes: "In and the Tosefta, the Sifra and the Sifrei, in all these are explained the forbidden, the clean and the unclean, the liabilities and lack of liability, the unfit and fit, as handed down from person to person from the mouth of Moses our teacher at Sinai." But the verdict of modern scholarship is that the halakhah has had a history and that it is possible to trace the stages in it's development with a considerable degree of success.