After it a voice roareth — i.e., the thunderclap which follows the lightning-flash.
And he stayeth them not (or will not stay them) when his voice is heard. — What does this mean? We understand it, “Yet none can track them (i.e., the thunder and the lightning) when His voice is heard. They travel in paths which none can explore. Vivid as the lightning is, who shall pursue its course?”