11 “For the law was given by Moses;” which law held the guilty. For what says the apostle? “The law entered that the offense might abound.” It was a benefit to the proud that the offense abounded, for they gave much to themselves, and, as it were, attributed much to their own strength; and they were unable to fulfill righteousness without the aid of Him who had commanded it. God, desirous to subdue their pride, gave the law, as if saying: Behold, fulfill, and do not think that there is One wanting to command. One to command is not wanting, but one to fulfill.
Source: Tractates on the Gospel of John (New Advent)