Luther on self-justification

Since we are on the topic of Luther, thought I'd throw this in there. This is from Luther's 'Sum of a Christian Life'.

"Even though we are now in faith....the heart is always ready to boast of itself before God and say: After all, I have preached so long and lived so well and done so much, surely he will take this into account. But it cannot be done. With men you may boast. But when you come before God, leave all that boasting at home and remember to appeal from justice to grace.

But Let anybody try this and he will see and experience how exceedingly hard and bitter it is for a man, who all his life has been mired in his work righteousness, to pull himself out of it and with all his heart rise up through faith in this one Mediator. I myself have been preaching and cultivating the Gospel for almost 20 years and still I feel the old clinging dirt of wanting to deal so with God that I may contribute something, so that he will have to give me his grace in exchange for my holiness. And stil I cannot get it into my head that I should surrender myself completely to sheer grace; yet I know that this is what I should and must do."