“I have elsewhere dealt at length with this Merkabah-mysticism of the so- called Hekhaloth literature, and shown that a genuine and unbroken chain of tradition links these writings to the secret doctrine of the Talmud. Large parts of this literature still belong to the talmudic period itself, and the central ideas of these texts go back to the first and second centuries.
To be sure, these texts, which in their present form belong in part to the genre of apocalyptic pseudepigraphy, are not always as old as they pretend to be. But even in these later adaptations, the underlying traditional material dates back to the period indicated. The mystical hymns found in several of the most important texts may definitely be traced back at least to the third century; here it is the literary form itself that militates against the idea of a later revision. The conceptions that find expression here surely were not developed later; in fact, they may date from a much earlier time.
These writings contain instructions for obtaining the ecstatic vision of the celestial regions of the Merkabah. They describe the peregrinations of the ecstatic through these regions: the seven heavens and the seven palaces or temples, Hekhaloth, through which the Merkabah mystic travels before he arrives at the throne of God. Revelations are made to the voyager concerning the celestial things and the secrets of the Creation, the hierarchy of the angels, and the magical practices of theurgy.
Having ascended to the highest level, he stands before the throne and beholds a vision of the mystical figure of the Godhead, in the symbol of the “likeness as the appearance of a man” whom the prophet Ezekiel was permitted to see upon the throne of Merkabah. There he receives a revelation of the “measurement of the body,” in Hebrew Shi’ur Qomah, that is, an anthropomorphic description of the divinity, appearing as the primal man, but also as the lover of the Song of Songs, together with the mystical names of his limbs.
The age of this Shi’ur Qomah mysticism, which scandalized the consciousness of later, “enlightened” centuries, may now be fixed with certainty. Contrary to the views that once prevailed, it must be dated to the second century, and certainly not later. It is undoubtedly connected with the interpretation of the Song of Songs as a mystical allegory of God’s relation with Israel.
Just as in the earliest days God revealed himself to the entire community of Israel, as was the case at the time of the Exodus from Egypt, where he was visibly manifest upon his Merkabah (this idea is attested in midrashic interpretations that undoubtedly go back to the tannaim), so is this revelation repeated in the relations between God and the mystic initiated into the secrets of the Merkabah.
The most important fragments of these descriptions transmitted in the Shi’ur Qomah make explicit reference to the depiction of the lover in many passages of the Song of Songs; this depiction thus offers a biblical veneer for what are evidently theosophic mysteries whose precise meaning and exact connections still escape us.”
–Gershom Scholem, Origins of the Kabbalah, 1987, pp. 19-21.