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.
Martin LutherThe Holy Spirit is no skeptic. He has written neither doubt nor mere opinion into our hearts, but rather solid assurances, which are more sure and solid than all experience and even life itself.
Martin Luther