We are playing around in mud and we think that we are clean ("good") because we see the world playing around in manure sludge.
St. Francis said that as God is the Light, as we come closer to him, it is as if we bring a light closer and closer to us. When we look at ourselves in the mirror, the less light we have, the less imperfections we see, the more perfect we think we are. As we add (receive) more light, get closer to God, we begin to see more and more of our imperfections, wrinkles, scars, pimples, blackheads, pores. We are blind as to what we really are. When St. Francis died, he was convinced that he deserved Hell, and entrusted himself to God’s Mercy. He knew that he was not clean because he compared himself to the God he was so close to. ST. FRANCIS OF ASSISI!