1. _General principles_ (vv. 17-20). After blessing comes obligation--after beatitude, law. It is the same order as of old. The old covenant was in its origin and essence a covenant of promise, of blessing. Mercy, not duty, was its key-note. When God called Abraham to the land of promise, His first word was: "I will bless thee, and make thy name great; and thou shalt be a blessing" (Gen. xii. 2). Later on came the obligation resulting, as in Genesis xvii. 1: "Walk before me, and be thou perfect." So in the history of the Nation, the promise came first and the law followed it after an interval of four hundred years--a fact of which special use is made by the Apostle Paul (Gal. iii. 17, 18). The Mosaic dispensation itself began by an acknowledgment of the ancient promise ("I am the God of your fathers"--Ex. iii. 6), and a fresh declaration of Divine mercy ("I know their sorrows, and am come to deliver them"--Ex. iii. 7, 8). When Mount Sinai was reached, the entire covenant was summarised in two sentences, the first reciting the blessing, the second setting forth the resulting obligation: "Thus shalt thou say to the house of Jacob, and tell the children of Israel; Ye have seen what I did unto the Egyptians, and how I bare you on eagles' wings, and brought you unto Myself. Now, therefore, if ye will obey My voice indeed, and keep My covenant, then ye shall be a peculiar treasure unto Me above all people" (Ex. xix. 3-5). The very Decalogue itself is constructed on the same principle; for before a single commandment is given, attention is called to the great salvation which has been wrought on their behalf: "I am the Lord thy God, which brought thee out of the land of Egypt, out of the house of bondage." Thus closely does the proclamation of the new kingdom follow the lines of the old; far above and beyond it in respect of development, in essence it is the same.