Martyn Lloyd-Jones, Seeking the Face of God: Nine Reflections on the Psalms (Wheaton:Crossway Books, 2005), p. 34
You will never make yourself feel that you are a sinner, because there is a mechanism in you as a result of sin that will always be defending you against every accusation. We are all on very good terms with ourselves, and we can always put up a good case for ourselves. Even if we try to make ourselves feel that we are sinners, we will never do it. There is only one way to know that we are sinners, and that is to have some dim, glimmering conception of God.