Rebbi — Rabbi Yehudah HaNasi — grappled with a verse that seems to describe God physically descending to Mount Sinai. (Exodus 19:20): "And the Lord went down upon Mount Sinai upon the top of the mountain. And the Lord called Moses to the top of the mountain, and Moses went up."
Is this to be understood literally? Did God actually relocate from heaven to the summit of a mountain in the Sinai desert? Rebbi rejected this emphatically. Can you really say such a thing?
He offered an a fortiori argument. Consider the sun — just one of God's servants, one of many celestial bodies He created. The sun makes its presence felt both in its own place (the sky) and outside its place (through its heat and light on earth). The sun does not physically move to the ground in order to warm it. If a mere servant of God can be present in multiple domains simultaneously, how much more so can the glory of the One who spoke and brought the world into being!
The "descent" at Sinai, then, must be understood figuratively. God did not physically relocate. His glory, His presence, His voice — these manifested on the mountain while He Himself remained transcendent and everywhere. The language of "going down" is a concession to human understanding, a way of describing an experience that has no precise parallel in human life. The mountain felt God's presence. That does not mean God was contained by the mountain.