I'm reading Thomas Watson's terrific book on the Lord's Prayer
Here's a keeper:
"Prayer is the gun we shoot with, fervency is the fire that discharges it, and faith is the bullet which pierces the throne of grace. Prayer is the key of heaven, faith is the hand that turns it....If a poor handycraftsman, who lives by his labour, has spoiled his tools so that he cannot work, how shall he subsist? Prayer is the tool we work with, which procures all good for us; but unbelief spoils and blunts our prayers, and then we get no blessing from God" (pg32)
All this from his meditation on the little "our" in "Our Father which art in heaven" -- the our makes it the prayer of personal faith and putting personal trust in a living God.
Soli Deo Gloria