Ver. 20. That his heart be not lifted up above his brethren— Not imagining himself to be above all laws, nor slighting his subjects as unworthy of his notice; but taking due care to promote their happiness: for, "as the Scriptures," says Maimonides, "provided that the king should have great honour done him, obliging all to reverence him, so it commands him to be lowly in heart, and not to carry himself insolently. Let him be gracious, and full of clemency to little and great: so shall he go out, and come in, with the love and good wishes of them all." To which Nachmanides adds this pious reflection, "If the Scripture deters kings from pride and haughtiness of heart, how unbecoming is it in other men, who are far inferior to them!"
That he may prolong his days,—he, and his children— We see from this, that God designed to give that family, whom he should choose, an hereditary right to the throne; but under the express condition of a sincere obedience to the laws. Nothing, certainly, is more proper to preserve a family in the possession of sovereign authority, than an inviolable attachment to the laws, both human and divine; for, as one of the ancients has well expressed it, "To cause the laws to reign, is, in some sort, to make God himself reign with the laws. It is, as it were, to raise a wild beast to the government, to submit every thing to the empire of a man without any other rule than his own will." See Aristotle's Polit. lib. iii. c. 16. Princes ought, above all things, to study to gain the affections of their people by their humility and clemency. It was good counsel given to Alexander the Great, that he should rather attach his subjects to him by the mildness of his government, than reign over them with a severe and despotic power; since it is very useless to endeavour to reign over the bodies of men, as he is always the master of these who reigns in their hearts; "gain, therefore, their hearts by your clemency," said the adviser to the conqueror, "and all the rest will follow." See Rabbi Jedajah in Mibcah Happeninim, and Selden in Success in Pontif. lib. ii. c. 1.