Faced with God's fascinating and mysterious presence, man discovers his own insignificance. Before the burning bush, Moses takes off his sandals and veils his face in the presence of God's holiness.[13] Before the glory of the thrice-holy God, Isaiah cries out: "Woe is me! I am lost; for I am a man of unclean lips."[14] Before the divine signs wrought by Jesus, Peter exclaims: "Depart from me, for I am a sinful man, O Lord."[15] But because God is holy, he can forgive the man who realizes that he is a sinner before him: "I will not execute my fierce anger. . . for I am God and not man, the Holy One in your midst."[16] The apostle John says likewise: "We shall. . . reassure our hearts before him whenever our hearts condemn us; for God is greater than our hearts, and he knows everything."[17]