Isaiah was called by God to be a prophet but felt unworthy.  Isaiah had a vision of a seraph using tongs to take a coal from the fire on the altar and sealing his lips with it, thereby purifying him.  Isaiah's prophecies included the "Peaceable Kingdom," where all of Creation lives in harmony. The lion and the lamb lie down together and swords are beaten into plowshares, as depicted by the anvil and sword.