Grace is mingled with corruption

"But grace is not only little, but mingled with corruption; therefore a Christian is said to be smoking flax. So we see that grace does not do away with corruption all at once, but some is left for believers to fight with. The purest actions of the purest men need Christ to perfume them; and this is his office. When we pray, we need to pray again for Christ to pardon the defects of our prayers."

From The Bruised Reed, by Richard Sibbes.