“Bear one another’s burdens, and in this way you will fulfill the law of Christ,” specifically the law of love. But if loving one’s neighbor fulfills the Law and the love of one’s neighbor is especially urged in the Old Testament also (in which love, the same Apostle says elsewhere, all the commandments of the Law are summed up), then it is clear that the Scripture given to the earlier people is also the law of Christ, which he came to fulfill by love when it was not being fulfilled by fear. The same Scripture and the same commandment, then, is called the Old Testament when it weighs down slaves panting for earthly goods, and the New Testament when it lifts up free people ardent for eternal goods.
SAINT AUGUSTINE Commentary on Galatians