Mar'ah comes from ra'ah, to see, and Hebrew uses it for two things English keeps apart: the vision a prophet receives (Numbers 12:6, Genesis 46:2, Ezekiel 1:1) and the polished bronze mirror a person looks into (Exodus 38:8, where the serving women's mirrors are melted down into the laver). The doubleness is not an accident of vocabulary. It is a statement about what prophetic sight is like. A bronze mirror returns a real image, but reversed, dimmed, requiring interpretation. So does a vision.

Numbers 12:6-8 builds a whole theology on the word. Ordinary prophets receive HaShem ba-mar'ah, in the vision, and ba-chalom, in the dream: true sight, indirect grade. Moshe alone receives peh el peh, mouth to mouth, and mar'eh, clear seeing, not in riddles. When Sha'ul (Paul) writes that now we see by means of a mirror but then face to face (1 Corinthians 13:12), he is not saying our sight is fogged. He is quoting the Torah's two grades of sight and telling us which one we currently hold, and which one the New Covenant is carrying us toward.