In addition to the common theme of purity, the Babylonian Talmud expands on the exemption of the first-born Levite, or Kohen. The child of a Levite mother, or Kohenim, regardless whether or not the father is a Levite or Israelite, is automatically exempt from the "toll". This exemption is due to the notion that first-born males are already born in the service of God thus redemption is not needed.
