18. As the prayer goes forward, we ask and say, "Give us this day our daily bread." And this may be understood both spiritually and literally, because either way of understanding it is rich in divine usefulness to our salvation. For Christ is the bread of life; and this bread does not belong to all men, but it is ours. And according as we say, "Our Father," because He is the Father of those who understand and believe; so also we call it "our bread," because Christ is the bread of those who are in union with His body.