The seraphim, like court heralds, announce Yahweh’s presence. This is a formality, not a necessary task, because Isaiah understands at a glance who he was. The proclamation that “the whole earth is full of his glory” emphasizes its extent and impact, reinforcing the need of the seraphim to be covered. This description is probably meant to parallel the way earthly kings were announced. The proclamation declares Yahweh as the heavenly king, as does the very presence of a throne.