Ambrose of Milan : Therefore Jacob, who had purified his heart of all pretenses and was manifesting a peaceable disposition, first cast off all that was his, then remained behind alone and wrestled with God. For whoever forsakes worldly things comes nearer to the image and likeness of God. What is it to wrestle with God other than to enter upon the struggle for virtue, to contend with one who is stronger and to become a better imitator of God than the others are? Because Jacob's faith and devotion were unconquerable, the Lord revealed his hidden mysteries to him by touching the side of his thigh. For it was by descent from him that the Lord Jesus was to be born of a virgin, and Jesus would be neither unlike nor unequal to God. The numbness in the side of Jacob's thigh foreshadowed the cross of Christ, who would bring salvation to all people by spreading the forgiveness of sins throughout the whole world and would give resurrection to the departed by the numbness and torpidity of his own body. On this account the sun rightly rose on holy Jacob, for the saving cross of the Lord shone brightly on his lineage. And at the same time the Sun of justice rises on the person who recognizes God, because he is himself the everlasting Light. — On Jacob and the Blessed Life