HaLeivi: I take back the word “heter,” it was bad phrasing. What I meant was, usually when nistar differs from nigleh — especially l’hakel, which it is here since the gemara calls it a b’dieved not to here yourself — the obvious question is “why?” As for the zohar being no different than a baraisa, I have a question for you: for purposes of din, is it considered a medrash halacha (like sifra, mechilta, etc) or a medrash aggada (like medrash rabba, tanchuma etc.) I’ve seen it treated both ways by today’s rabbonim; do you know of earlier sources?
myfriend: You seem to be disagreeing with the word “scientific” more than with anything I am actually saying. The geonim were in Bavel. As the masses of yidden moved to France and Germany, the rabbonim and yeshivos moved with them. You may have noticed that after the geonim, most of the rishonim live in ashkenaz. Rashi– Learned in Mainz, lived in the Alsace-Lorraine region. Most of the baalei tosfos — northern France. Anyone who learns rishonim knows where they lived because references pop up. If you want seforim that deal exclusively with the subject, the Chida wrote one (forget the title, sorry) and more recently we have the Legacy of Sinai series in English which charts the mesorah from Moshe Rabeinu to Rabbeinu Moshe ben Maimon to Rav Moshe Feinstein. There is also Toldos am Olam in Lashon Kodesh.