That Quackdoctor, Reason

"We comfort the afflicted sinner in this manner: Brother, you can never be perfect in this life, but you can be holy. He will say: 'How can I be holy when I feel my sins?' I answer: You feel sin?
That is a good sign. To realize that one is ill is a step, and a very necessary step, toward recovery.
'But how will I get rid of my sin?' he will ask. I answer: See the heavenly Physician, Christ, who heals the broken-hearted. Do not consult that Quackdoctor, Reason. Believe in Christ and your sins will be pardoned. His righteousness will become your righteousness, and your sins will become His sins."    -Dr. Martin Luther, from his Commentary on Galatians 3:6