Austin Farrer on petitionary prayer
It is difficult to keep grace, not to get it, and there is always more. There are other things more genuinely difficult in prayer; for sometimes we are deeply concerned to have what is not ready set out for us to carry away, such as health in sickness, success in an undertaking; and here it is a matter of discovering what God has given us to carry off: we begin with what we want, but in praying, and not perhaps the first time, discover what God has designed to give. And, in the end, this is never worse, for through all his gifts rightly taken, he gives himself at last.
from The Brink of Mystery, (SPCK, 1967), 170.