When the Tabernacle was set up and all its furnishings put in place, Moses performed the rites that inaugurated the Tabernacle and the priests. As a sign that all was done properly and the Tabernacle was indeed ready to serve as a place where G‑d’s presence could be felt, a cloud materialized and hovered above the Tabernacle.
The Mystical Dimension
וְלֹא יָכֹל מֹשֶׁה לָבוֹא אֶל אֹהֶל מוֹעֵד כִּי שָׁכַן עָלָיו הֶעָנָן וּכְבוֹד ה' מָלֵא אֶת הַמִּשְׁכָּן: (שמות מ:לה)
Moses could not enter the Tent of Meeting, for the cloud had rested upon it, and G‑d’s glory filled the Tabernacle. Exodus 40:35

Clouds conceal what is within and behind them, and are therefore a metaphor for the incomprehensible infinity of G‑d, which is beyond the ability of the human mind to grasp. This is why once G‑d’s presence rested upon the Tabernacle, even Moses could not enter it.

Yet, in the beginning of the very next book of the Torah, Leviticus, G‑d calls to Moses from within the Tabernacle, thereby enabling him to enter it despite the Divine cloud resting on it and G‑d’s glory filling it.

We are taught that in the absence of the Tabernacle (and its successor, the holy Temple in Jerusalem), G‑d reveals Himself to us through the Torah. We all possess an inner “Moses,” i.e., the ability to selflessly devote ourselves to G‑d and His will. G‑d calls out to us through this inner Moses, enabling us to enter the mysteries of the Torah and commune with His presence. By fulfilling G‑d’s commandments and praying, we refine ourselves so that we can perceive G‑d’s presence ever clearer in our study of His Torah.1