The Calling of Isaiah

Isaiah had a position at the court of king Uzziah. After Uzziah's death Isaiah's future became uncertain. In a vision he saw God and a number of angels. Isaiah tells them he lives among a people "of unclean lips". One of the angels then approaches Isaiah and touches his lips with a hot coal: Isaiah's lips and thereby he himself are now cleared of any sin. Isaiah immediately offers to become a prophet.

This is one of Tiepolo's ceiling paintings in the palace of the bishop of Udine.