Two biblical verses about Sinai appear to contradict each other directly. (Exodus 20:19) says God spoke "from the heavens." But (Exodus 19:20) says "the Lord went down upon Mount Sinai." Was God in heaven or on the mountain?
Rabbi Yishmael resolved the contradiction with a third verse. (Deuteronomy 4:36): "From the heavens He made you hear His voice to exhort you, and on the earth He showed you His great fire, and His words you heard from the midst of the fire." This verse combines both elements — heavenly voice and earthly fire — showing that the Sinai revelation operated simultaneously in two domains.
God's voice came from heaven. His fire appeared on earth. The Israelites heard the words from within the fire that burned on the mountain, while the source of those words remained in the heavens above. There was no contradiction because the event itself transcended the normal categories of above and below.
Rabbi Yishmael's method — resolving two contradictory verses through a third — became one of the foundational rules of rabbinic interpretation. When Scripture seems to say two incompatible things, the answer is not to choose one over the other but to find a third passage that synthesizes both. The Sinai revelation was the perfect case study. Heaven and earth met at that moment. God was simultaneously above and present. The mountain burned with heavenly fire while the voice echoed from the sky. Sinai was the place where the boundary between heaven and earth temporarily ceased to exist.