When I am assailed with heavy tribulations, I rush out among my pigs rather than remain alone by myself. The human heart is like a millstone in a mill: when you put wheat under it, it turns and grinds and bruises the wheat to flour; if you put no wheat, it still grinds on, but then 'tis itself it grinds and wears away. So the human heart, unless it be occupied with some employment, leaves space for the devil, who wriggles himself in and brings with him a whole host of evil thoughts, temptations, and tribulations, which grind out the heart.
Martin LutherIt is a tremendously hard thing to pray aright, yea, it is verily the science of all sciences.
Martin Luther