Maggid of Mezrich Ohr Torah Parshat Beha'alotcha
ג וְהָאִישׁ מֹשֶׁה, עָנָו מְאֹד--מִכֹּל, הָאָדָם, אֲשֶׁר, עַל-פְּנֵי הָאֲדָמָה.
" Now the man Moses was very humble, above all the men that were upon the face of the earth-" Numbers 12:3
An interpretation of this is that there are two levels to humility. The first is that ones thoughts should be entirely [directed] above and separate from the material even in lower matters.
On the second level, one is not separated from the material that much. This is the meaning of when it says Moshe Moshe [at the burning bush] without a line separating [the two instances of the name]. When Jacobs name is repeated (gen. 46:2) [cfx. 22:11, I Samuel 3:10] there is a separating line. For there is a Moshe above and a Moshe below, and a Jacob above and a Jacob below. Therefore with Moshe there is no separating line for he was entirely one [unified]. Above and below he was one. For he was entirely above, and he was separated from the material even in lower matters, and it is obvious [that he was this way] in upper matters as well.
In spite of this he held himself to the attribute of humility even in upper matters.
"...than all men [literally "all man] who were on the face of the earth." "Man" here is referring to his thoughts all of which were "on the face of the earth". This means Moshe thought of himself as lower even than that person who is entirely below.