Parsha Mitzvot: Shemot: Shemonah Perakim: Prophecy
In many places in the midrash and the Aggadah, including some passages quoted in the Talmud, it is said that there are prophets who see God behind many veils. and others who see God with fewer veils. The difference depends on the extent of their closeness to God and the elevated level of their prophecy. Thus it is said that Moses saw God behind one clear and shiny transparent veil.
This is what is meant by the expression that Moses look through the brilliant looking glass; the term looking glass refers to a lens made from a shiny material like diamonds or crystal.
The intent of this statement is that there are intellectual virtues and ethical virtues; conversely there are intellectual shortcomings such as foolishness, naïveté, difficulty in understanding, and ethical shortcomings; gluttony, pride, anger, wrath, brashness, and the love of money and the like. All of these shortcomings are veils that separate between us and Him.
A prophet will not prophecy until he has acquired all of the intellectual virtues and most of the ethical virtues. (Chapter Seven: Veils Of Our True Selves And How They Operate)