But the treacherous and self-seeking craft of the other brother is as repulsive; the cold-blooded, calculating spirit that can hold every appetite in check, that can cleave to one purpose for a life-time, and, without scruple, take advantage of a twin-brother's weakness. Jacob knows his brother thoroughly, and all his knowledge he uses to betray him. He knows he will speedily repent of his bargain, so he makes him swear he will abide by it. It is a relentless purpose he carries out--he deliberately and unhesitatingly sacrifices his brother to himself. Still, in two respects, Jacob is the superior man. He can appreciate the birthright in his father's family, and he has constancy. Esau might be a pleasant companion, far brighter and more vivacious than Jacob on a day's hunting; free and open-handed, and not implacable; and yet such people are not satisfactory friends. Often the most attractive people have similar inconstancy; they have a superficial vivacity, and brilliance, and charm, and good-nature, which invite a friendship they do not deserve. Parents frequently make the mistake of Isaac, and think more highly of the gay, sparkling, but shallow child, than of the child who cannot be always smiling, but broods over what he conceives to be his wrongs. Sulkiness is itself not a pleasing feature in a child's character, but it may only be the childish expression of constancy, and of a depth of character which is slow to let go any impression made upon it. On the other hand, frankness and a quick throwing aside of passion and resentment are pleasing features in a child, but often these are only the expressions of a fickle character, rapidly changing from sun to shower like an April day, and not to be trusted for retaining affection or good impressions any longer than it retains resentment.