Analysis of information sources in references of the Wikipedia article "Golden mean (Judaism)" in English language version.
This rabbinic depiction of the "middle path" is Soloveitchik's adaptation of the Maimonidean "golden mean." Maimonides adopts from Aristotle's Ethics refracted through the Islamic theology of 'Al Farabi and others.
Maimonides adopts the Aristotelian notion that to become morally virtuous humans must practice the middle way (Weiss and Butterworth 1975)
Many have searched for the exact sources of the Rambam and have found that the Rambam bases much, if not most, of his explanations regarding the proper character traits and the golden mean on the works of Aristotle's Ethics and Al-Farabi's Fusul al-Madani (See Raymond L. Weiss's Maimonides' Ethics: The Encounter of Philosophic and Religious Morality, p. 23, for comparisons of the works.)
According to Heschel (1982), Maimonides took this idea of the middle way from Aristotle - but with some specific variations.