NOTES for Exo 40:1-38
The completion of the construction of the Tabernacle was marked by the appearance of God's presence over it. Later, already in the priestly environment, it would be called "the glory of Yahweh" (in English translations, as a rule, "the glory of the Lord"). Here, however, it is simply described as it was seen, perhaps not by everyone, but at any rate by many; otherwise Exodus would not speak of it with such confidence. This is the same Presence that was first revealed at Sinai to Moses when he was shepherding his father-in-law's sheep.
Moses saw it in the form of a shining cloud descending on a bush, and here too there is a cloud, though its radiance, judging by the description, is visible mainly at night, while by day it appears precisely as a cloud, a light mist. In any case, this is a visible Presence, something by which God Himself marks on earth the place He has chosen. To that place those who want to meet Him face to face are to come. Of course, the point is not that God is light or any kind of radiation at all. God's presence is not a physical or psychic phenomenon, although without physical and psychic nature we would see nothing at all.
The point here is God's will: the very will that created the world and humanity, and then created God's people and led them out of Egypt. Spirit has neither color, nor shape, nor nature; therefore God as He is remains invisible to us. But where His will acts, something visible can also appear, if only He wills it. And He wills a meeting; He wills to overcome the abyss that separates us from Him. His will is directed toward overcoming it. It is directed into the world, and not merely into the world, but into that part of it where He wants to create a bridge connecting Him with us.
Meanwhile, a will directed toward creation gives rise to what we perceive as form, as an object, as something. As Presence. A Presence behind which stands a will, the will of the One who teaches the people to follow Him. It is no accident that the story mentions how the Hebrews went through the wilderness: when the cloud moved, they moved too; when it stood still, they stood still as well. To move only together with God and only after Him: such is the path of the Exodus. If one walks this way, then God will be visible, and God's presence will become reality.