Guide for the Perplexed, by Moses Maimonides, Friedländer tr. [1904], at sacred-texts.com
THE term regel is homonymous, signifying, in the first place, the foot of a living being; comp. "Foot for foot" (Exod. xxi. 24). Next it denotes an object which follows another: comp. "And all the people that follow thee" (lit. that are at thy feet) (ib. xi. 18). Another signification of the word is "cause"; comp. "And the Lord hath blessed thee, I being the cause" (leragli) (Gen. xxx. 30), i.e., for my sake; for that which exists for the sake of another thing has the latter for its final cause. Examples of the term used in this sense are numerous. It has that meaning in Genesis xxxiii. 14, "Because (leregel) of the cattle that goeth before me, and because (leregel) of the children."
Consequently, the Hebrew text, of which the literal rendering is: "And his feet shall stand in that day upon the Mount of Olives" (Zech. xiv. 4) can be explained in the following way: "And the things caused by him (raglav) on that day upon the Mount of Olives, that is to say, the wonders which will then be seen, and of which God will be the Cause or the Maker, will remain permanently." To this explanation does Jonathan son of Uziel incline in paraphrasing the passage," And he will appear in his might on that day upon the Mount of Olives. He generally expresses terms denoting those parts of the body by which contact and motion are effected, by "his might" [when referring to God], because all such expressions denote acts done by His Will.
In the passage (Exod. xxiv. 10, lit., "And there was under his feet, like the action of the whiteness of a sapphire stone"), Onkelos, as you know, in his version, considers the word (raglav) "his feet" as a figurative expression and a substitute for "throne"; the words "under his feet" he therefore paraphrases, "And under the throne of his glory." Consider this well, and you will observe with wonder how Onkelos keeps free from the idea of the corporeality of God, and from everything that leads thereto, even in the remotest degree. For he does not say, "and under His throne"; the direct relation of the throne to God, implied in the literal sense of the phrase "His throne," would necessarily suggest the idea that God is supported by a material object, and thus lead directly to the corporeality of God: he therefore refers the throne to His glory, i.e., to the Shekhinah, which is a light created for the purpose.
Similarly he paraphrases the words, "For my hand I lift up to the throne of God" (Exod. xvii. 16), "An oath has been uttered by God, whose Shekhinah is upon the throne of his glory." This principle found also expression in the popular phrase, "the Throne of the Glory."
We have already gone too far away from the subject of this chapter, and touched upon things which will be discussed in other chapters; we will now return to our present theme. You are acquainted with the version of Onkelos [of the passage quoted]. He contents himself with excluding from his version all expressions of corporeality in reference to God, and does not show us what they (the nobles of the children of Israel Exod. xxiv. 10) perceived,
or what is meant by that figure. In all similar instances Onkelos also abstains from entering into such questions, and only endeavours to exclude every expression implying corporeality; for the incorporeality of God is a demonstrative truth and an indispensable element in our faith; he could decidedly state all that was necessary in that respect. The interpretation of a simile is a doubtful thing: it may possibly have that meaning, but it may also refer to something else. It contains besides very profound matter, the understanding of which is not a fundamental element in our faith, and the comprehension of which is not easy for the common people. Onkelos, therefore, did not enter at all into this subject.
We, however, remaining faithful to our task in this treatise, find ourselves compelled to give our explanation. According to our opinion "under his feet" (raglav) denotes "under that of which He is the cause," "that which exists through Him," as we have already stated. They (the nobles of the children of Israel) therefore comprehended the real nature of the materia prima, which emanated from Him, and of whose existence He is the only cause. Consider well the phrase, "like the action of the whiteness of the sapphire stone." If the colour were the point of comparison, the words, "as the whiteness of the sapphire stone" would have sufficed; but the addition of "like the action" was necessary, because matter, as such, is, as you are well aware, always receptive and passive, active only by some accident. On the other hand, form, as such, is always active, and only passive by some accident, as is explained in works on Physics. This explains the addition of "like the action" in reference to the materia prima. The expression "the whiteness of the sapphire" refers to the transparency, not to the white colour: for "the whiteness" of the sapphire is not a white colour, but the property of being transparent. Things, however, which are transparent, have no colour of their own, as is proved in works on Physics: for if they had a colour they would not permit all the colours to pass through them nor would they receive colours: it is only when the transparent object is totally colourless, that it is able to receive successively all the colours. In this respect it (the whiteness of the sapphire) is like the materia prima, which as such is entirely formless, and thus receives all the forms one after the other. What they (the nobles of the children of Israel) perceived was therefore the materia prima, whose relation to God is distinctly mentioned, because it is the source of those of his creatures which are subject to genesis and destruction, and has been created by him. This subject also will be treated later on more fully.
Observe that you must have recourse to an explanation of this kind, even when adopting the rendering of Onkelos, "And under the throne of His glory"; for in fact the materia prima is also under the heavens, which are called "throne of God," as we have remarked above. I should not have thought of this unusual interpretation, or hit on this argument were it not for an utterance of R. Eliezer ben Hyrcanus, which will be discussed in one of the parts of this treatise (II. chap. xxvi.). The primary object of every intelligent person must be to deny the corporeality of God, and to believe that all those perceptions (described in the above passage) were of a spiritual not of a material character. Note this and consider it well.