'The liver,' as in Exodus 29:13, signifies interior purification, and 'the caul above the liver,' the inferior good of the external or natural self.

(Referencias: Arcana Coelestia 10031)

4418. Those in hell are said to be in darkness, but they are said to be in darkness because they dwell in falsities. For just as light corresponds to truths so darkness corresponds to falsities; and those in hell dwell in an inferior light, as stated above, like the yellow light of burning coal and sulphur. This light is what 'darkness' is used to mean, for their understanding is dependent on the light and therefore the sight this gives them, since that darkness and their understanding correspond to each other. The word darkness is used because light like this turns into darkness at the approach of heavenly light.