A teaching of the Baal Shem Tov, of blessed memory[1]:
“As waters reflect the face to the face, so does the heart of man reflect to man.” When a person stands beside water, his reflection appears large upon the water, when he lowers himself his reflection becomes smaller and the lower he bends toward the water, the smaller his reflection becomes, until when he places his face upon the water, the reflection of the face in the water becomes equal to his.
So is it regarding the heart of man to man. When a person regards himself as being great, then his fellow is also great. When he lessens himself in his fellow’s presence, then his fellow lessens himself likewise. Finally, they become equal and there is equanimity between them.
Scripture states about Moshe, “And HaShem spoke to Moshe face to face, like a man speaking to his friend.” That is, according to how small a person makes himself in his fellow’s presence, so will his fellow make himself small, until they become equal, that is, face to face, as explained above. Likewise, Moshe made himself small in the presence of the Creator. Therefore, the Creator made Himself small for Moshe, and spoke with him face to face.
This also is the meaning of King David’s statement, “I have set HaShem before me always.” That is, “I set HaShem before me always and understand that, so to speak, HaShem lowers and makes Himself small, to bestow His goodness upon me. This being the case, it is only proper that I respond by making myself small, thus attaining equanimity.
[1] From the book Ohr HaChochmah