And it came to pass on the third day in the morning, that there were thunders and lightnings, and a thick cloud upon the mount, and the voice of the trumpet exceedingly loud; so that all the people that were in the camp trembled.
All Commentaries on Exodus 19:16 Go To Exodus 19
Augustine of Hippo
AD 430
Again God produces the ordinary lightnings and thunders. But because they were done in an unusual manner on Mt. Sinai, and those voices were spoken there without a confused noise but in such a manner that it was evident from the most unmistakable proofs, … certain significant meanings were attached to them. Then they were miracles. .