Thunders. Verses 16-20 deal with the manifestations of the divine presence upon Sinai. In revealing Himself to man the Lord employs various methods. To Elijah He came as “a still small voice” (1 Kings 19:12), to the prophet Daniel and the apostle John He used visions, to the disciples He spoke directly through His Son. To Paul, God appeared in ecstatic vision, the apostle hearing “unspeakable words, which it is not lawful for a man to utter” (2 Cor. 12:1-5). Here, when God would impress all with the importance and majesty of His law as the constitution of His spiritual kingdom, He appears with terrifying grandeur (Heb. 12:18-21).