” … We have no reason to believe that this gnostic theosophy still possessed any creative impulses of a decisive character after the third century. The productive development of these ideas evidently occurred on Palestinian soil, as the analysis of the Hekhaloth texts proves. At a later date in Palestine as well as in Babylonia, we still encounter literary elaborations of this old material, some of which underwent metamorphosis into edifying tracts. But we no longer find any new ideas.
The practical realization of these heavenly voyages of the soul and the “vision of the merkabah,” sefiyyath merkabah, maintained itself also in the post-talmudic period, and some scattered reports concerning practices of this kind, which are by no means to be regarded as mere legends, have come down to us from as late as the twelfth and the thirteenth centuries from France and Germany.
These old texts, augmented by all kinds of later additions, were known to the Middle Ages in the form given to them in the late talmudic and early post-talmudic periods as “Greater Hekhaloth,” “Lesser Hekhaloth,” Shi’ur Qomah, Book of the Merkabah and under other titles as well as in different versions. These texts were considered to be ancient, esoteric paragraphs of the Mishnah, and in the superscriptions of the oldest manuscripts they are here and there designated as “halakhoth concerning the Hekhaloth.”
They enjoyed great authority and were in no way suspected of heresy. Manuscripts of these texts and the related theurgical literature were known in the Orient, as is proven by many fragments in the Cairo Grenizah, but also in Italy, in Spain, in France, and in Germany. In the twelfth century, texts of this kind circulated precisely in learned circles, where they were considered authentic documents of the old esoteric doctrines. It was therefore only to be expected that the earliest kabbalists would seek to establish a relationship with the traditions that enjoyed such high esteem.”
–Gershom Scholem, Origins of the Kabbalah, 1987, pp. 23-4.