There are many rabbinic attempts to define the two contradictory world views represented by Esau and Jacob. Some find it in Esau’s preference for this world, while Jacob prefers the world to come. Others find the difference in the words of Isaac (Genesis 27:22), “the voice is the voice of Jacob, but the hands those of Esau.” Jacob’s strength is in the vocal practice of prayer and learning, while Esau’s lies in the skill of his hands. See Babylonian Talmud, Gittin 57b, where the two can use each other’s “specialization.”