In the Rishonim [mediaeval authorities] there is an emphasis on Reason and Faith. But they do not mean faith in anything nor any reasonable sounding doctrines. As the Rambam puts it: "Just like one can not add nor subtract from the written Law so one can not add nor subtract from the Oral Law." So he means to eliminate pseudo Torah and books that pretend to be Torah. To him there is a cut-off point when the Oral Law was redacted. That means the Two Talmuds, and the Midrashim are the only real authentic Oral Law and everything else which claims to be Torah is Torah from the Dark Side. [Midrash means two things Midrash Agada and Midrash Halacha]. [Zohar does not count as midrash because of the phrase עם כל ד "although". That way of saying although was an invention of the Ibn Tibon family during the Middle Ages. In the time of the Mishna this was said as "אף על פי" or "אף על גב"
something is odd about mysticism. But I would rather not dismiss it in toto.
When the Rambam refers to Reason he also makes it clear he is referring to Aristotle [and to a lesser degree Plotinus]
