What Does Exodus 19:16 Mean?

And as the sound of the trumpet grew louder and louder, Moses spoke, and God answered him in thunder. The conversation between Moses and YHWH at the mountain, Moses speaks, God answers in thunder, is the Sinai covenant's most astonishing communication: the prophet's human voice answered by divine thunder.

The thunder-answer is God's theophanic voice: Psalm 29 ("the voice of the LORD is over the waters... the voice of the LORD is powerful... the voice of the LORD breaks the cedars") is the liturgical celebration of the divine-thunder-voice that Sinai first displayed in direct communication with Moses. Thunder is YHWH's voice, rather than natural phenomena.

The trumpet-sound growing louder as Moses speaks and God answers creates the theophany's intensification structure: the longer the Sinai encounter continues, the more overwhelming the trumpet becomes. The trumpet that is already "very loud" at the theophany's beginning grows even louder as Moses and YHWH converse. The intensification signals the covenant formation's approach to its climax: the Ten Commandments will be spoken from the mountain to the assembled community (chapter 20) as the culmination of the trumpet-growing-louder anticipation of chapter 19.

The Moses-speaks/God-answers pattern of verse 19 is the prototype of prophetic prayer: the prophet's spoken address to YHWH receives the divine response. Jeremiah 33:3 ("call to me and I will answer you, and will tell you great and hidden things that you have not known") formalizes what Sinai's Moses-calls/God-answers established: the covenant God who answered Moses in thunder is the God who answers all prophetic prayer. The thunder-answer at Sinai is the auditory evidence that YHWH is a God who responds when his prophet speaks.