After these things a son was born to Abraham, according to God's promise, of Sarah, and was called Isaac, which means _laughter_. For his father had laughed when he was promised to him, in wondering delight, and his mother, when he was again promised by those three men, had laughed, doubting for joy; yet she was blamed by the angel because that laughter, although it was for joy, yet was not full of faith. Afterwards she was confirmed in faith by the same angel. From this, then, the boy got his name. For when Isaac was born and called by that name, Sarah showed that her laughter was not that of scornful reproach, but that of joyful praise; for she said, "God hath made me to laugh, so that every one who hears will laugh with me."[301] Then in a little while the bond maid was cast out of the house with her son; and, according to the apostle, these two women signify the old and new covenants,--Sarah representing that of the Jerusalem which is above, that is, the city of God.[302] 32. _Of Abraham's obedience and faith, which were proved by the offering up of his son in sacrifice; and of Sarah's death._ Among other things, of which it would take too long time to mention the whole, Abraham was tempted about the offering up of his well-beloved son Isaac, to prove his pious obedience, and so make it known to the world, not to God. Now every temptation is not blameworthy; it may even be praiseworthy, because it furnishes probation. And, for the most part, the human mind cannot attain to self-knowledge otherwise than by making trial of its powers through temptation, by some kind of experimental and not merely verbal self-interrogation; when, if it has acknowledged the gift of God, it is pious, and is consolidated by stedfast grace and not puffed up by vain boasting. Of course Abraham could never believe that God delighted in human sacrifices; yet when the divine commandment thundered, it was to be obeyed, not disputed. Yet Abraham is worthy of praise, because he all along believed that his son, on being offered up, would rise again; for God had said to him, when he was unwilling to fulfil his wife's pleasure by casting out the bond maid and her son, "In Isaac shall thy seed be called." No doubt He then goes on to say, "And as for the son of this bond woman, I will make him a great nation, because he is thy seed."[303] How then is it said, "In Isaac shall thy seed be called," when God calls Ishmael also his seed? The apostle, in explaining this, says, "In Isaac shall thy seed be called, that is, they which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed."[304] In order, then, that the children of the promise may be the seed of Abraham, they are called in Isaac, that is, are gathered together in Christ by the call of grace. Therefore the father, holding fast from the first the promise which behoved to be fulfilled through this son whom God had ordered