Exodus 24:10

Moses, of course, might be thought to have seen God with bodily eyes, if not only the Wisdom of God which is Christ but even the wisdom itself … [which] can be seen with the eyes of the flesh, or because it is written of the elders of Israel that "they beheld the place where the God of Israel had stood" and that there was "under his feet as it were a work of sapphire stone and a likeness of the firmament of heaven." We might therefore be led to imagine that the Word and the Wisdom of God, who extends from end to end mightily and orders all things sweetly, stood in his own substance within the space of an earthly place. And thus the Word of God, through whom all things were made, is thought changeable so that now he draws himself together and now he expands. May God cleanse the hearts of his faithful from such thoughts! But, as we have often declared, all these visible and tangible signs were displayed through a creature that has been made subject, in order to signify the invisible and intelligible God, not only the Father but also the Son and the Holy Spirit, from whom are all things, through whom are all things, and in whom are all things. Since the creation of the world, the invisible attributes of God, his everlasting power also and divinity, are seen, being understood through the things that are made.

They saw the place where the God of Israel stood (so the LXX.), something that came near a similitude, but was not; whatever they saw, it was certainly something of which no image nor picture could be made, and yet enough to satisfy them that God was with them of a truth.

And they saw the God of Israel,....

They saw the God of Israel - The seventy elders, who were representatives of the whole congregation, were chosen to witness the manifestation of God, that they might be satisfied of the truth of the revelation which he had made of himself and of his will; and on this occasion it was necessary that the people also should be favored with a sight of the glory of God; see Exo 20:18. Thus the certainty of the revelation was established by many witnesses, and by those especially of the most competent kind.

And they saw the God of Israel - As they ate the sacrificial feast, the presence of Yahweh was manifested to them with special distinctness. In the act of solemn worship, they perceived that He was present with them, as their Lord and their Deliverer. It is idle to speculate on the mode of this revelation. That no visible form was presented to their bodily eyes, we are expressly informed, Deu 4:12; see Exo 33:20; compare Isa 6:1. The latter part of this verse may be read: “under His feet, it was like a work of bright sapphire stone, and like the heaven itself in clearness.” On the sapphire, see Exo 28:18; compare Eze 1:26. The pure blue of the heaven above them lent its influence to help the inner sense to realize the vision which no mortal eye could behold.