Rambam: Shemot: Moshe Hid His Face

Moreh Nevuchim – Guide to the Perplexed 1:5: When the person has achieved and acquired knowledge of the rules of logic and inference and of the various way of preserving himself from errors of the mind, he then should engage in the investigation of this subject.

When doing this he should not make categorical affirmations in favor of the first opinion that occurs to him and should not, from the outset, strain and impel his thoughts toward the apprehension of the Deity; he rather should feel awe and refrain and hold back until he gradually elevates himself.

It is in this sense that it is said, “And Moshe hid his face, for he was afraid to look upon God,” (Exodus 3:6) this being an additional meaning of the verse over and above its external meaning that indicates that he hid his face because of his being afraid to look upon the light manifesting itself – and not that the Deity, Who is greatly exalted above every deficiency, can be apprehended by the eyes. Moshe was commended for this, and God, may He be exalted, let overflow upon him so much of His bounty and goodness that it became necessary to say of him, “And the figure of the Lord shall he look upon.” (Numbers 12:8) The Sages, may their memory be blessed, have stated that this is a reward for his having at first hidden his face so as not to look upon God. (Berachot 7a)