C.S. Lewis, The Collected Letters of C. S. Lewis, Volume lll: Narnia, Cambridge, and Joy 1950-1963

"Remember He is the artist and you are only the picture. You can't see it. So quietly submit to be painted---i.e., keep fulfilling all the obvious duties of your station (you really know quite well enough what they are!), asking forgiveness for each failure and then leaving it alone.You are in the right way. Walk---don't keep on looking at it."