If there is one lesson we need to see here in this portion of Scripture, it is the fact that the Spirit and the flesh do not mix. Sarah giving birth to Isaac, the promised seed, is a type of salvation by grace through faith in Christ (“the seed”). Hagar, on the other hand, is used by the Apostle Paul as an allegory of the law and of the works of the flesh. Just as Abraham tried to accomplished God’s promise by the flesh through Hagar, so are all of those who trust the law and works to provide salvation. We must come to God, God’s way, through the Spirit. We see this as taught by Paul in Galatians 4:21-31; 5:1).