"In any study of the principles, and procedure of prayer, of its activities and enterprises, first place, must, of necessity, be given to faith. It is the initial quality in the heart of any man who essays to talk to the Unseen. He must, out of sheer helplessness, stretch forth hands of faith. He must believe, where he cannot prove. In the ultimate issue, prayer is simply faith, claiming its natural yet marvellous prerogatives -- faith taking possession of its illimitable inheritance. True godliness is just as true, steady, and persevering in the realm of faith as it is in the province of prayer. Moreover: when faith ceases to pray, it ceases to live.
Faith does the impossible because it brings God to undertake for us, and nothing is impossible with God. How great -- without qualification or limitation -- is the power of faith! If doubt be banished from the heart, and unbelief made stranger there, what we ask of God shall surely come to pass, and a believer hath vouchsafed to him'whatsoever he saith.'"
-from "The Necessity of Prayer"