Whoever confesses his sins . . . is already working with God. God indicts your sins; if you also indict them, you are joined with God. Man and sinner are, so to speak, two realities: when you hear “man” – this is what God has made; when you hear “sinner” – this is what man himself has made. Destroy what you have made, so that God may save what he has made. . . . When you begin to abhor what you have made, it is then that your good works are beginning, since you are accusing yourself of your evil works. The beginning of good works is the confession of evil works. You do the truth and come to the light.61St. Augustine, In Jo. ev. 12,13:PL 35,1491.
Taken from: http://www.scborromeo.org/ccc/ccc_toc.htm