_What then is the law?_ So the Jew might well exclaim. Paul has been doing nothing but disparage it.--"You say that the Law of Moses brings no righteousness or blessing, but only a curse; that the covenant made with Abraham ignores it, and does not admit of being in any way qualified by its provisions. What then do you make of it? Is it not God's voice that we hear in its commands? Have the sons of Abraham ever since Moses' day been wandering from the true path of faith?" Such inferences might be drawn, not unnaturally, from the Apostle's denunciation of Legalism. They were actually drawn by Marcion in the second century, in his extreme hostility to Judaism and the Old Testament. This question must indeed have early forced itself upon Paul's mind. How could the doctrine of Salvation by Faith and the supremacy of the Abrahamic Covenant be reconciled with the Divine commission of Moses? How, on the other hand, could the displacement of the Law by the Gospel be justified, if the former too was authorised and inspired by God? Can the same God have given to men these two contrasted revelations of Himself? The answer, contained in the passage before us, is that the two revelations had different ends in view. They are complementary, not competing institutes. Of the two, the Covenant of Promise has the prior right; it points immediately to Christ. The Legal economy is ancillary thereto; it never professed to accomplish the work of grace, as the Judaists would have it do. Its office was external, but nevertheless accessory to that of the Promise. It guarded and schooled the infant heirs of Abraham's Testament, until the time of its falling due, when they should be prepared in the manhood of faith to enter on their inheritance. "The law hath been our tutor for Christ, with the intent we should be justified by faith" (ver. 24). This aspect of the Law, under which, instead of being an obstacle to the life of faith, it is seen to subserve it, has been suggested already. "For I," the Apostle said, "_through law_ died to law" (ch. ii. 19). The Law first impelled him to Christ. It constrained him to look beyond itself. Its discipline was a preparation for faith. Paul reverses the relation in which faith and Law were set by the Judaists. They brought in the Law to perfect the unfinished work of faith (ver. 3): he made it preliminary and propædeutic. What they gave out for more advanced doctrine, he treats as the "weak rudiments," belonging to the infancy of the sons of God (ch. iv. 1-11). Up to this point, however, the Mosaic law has been considered chiefly in a negative way, as a foil to the Covenant of grace. The Apostle has now to treat of its nature more positively and explicitly, first indeed _in contrast with the promise_ (vv. 19, 20); and secondly, _in its co-operation with the promise_ (vv. 22-24). Ver. 21 is the transition from the first to the second of these conceptions.