[Karl Barth, the 20th-century theologian who pounded home the theme of God's sovereignty, saw no contradiction at all in a God who chooses to let prayers affect him.] He is not deaf, he listens; more than that, he acts. He does not act in the same way whether we pray or not. Prayer exerts an influence upon God's action, even upon his existence. That is what the word 'answer' means. ... The fact that God yields to man's petitions, changing his intentions in response to man's prayer, is not a sign of weakness. He himself, in the glory of his majesty and power, has so willed it.