Who is Satan from The Complete Poetry and Prose of William Blake and what is their importance?

Satan appears in Blake's, Throughout but not Everywhere. Blake notes that in Milton's writings, Satan is of the Elect class— one of the three classes of mankind, which include the elect, the reprobate and the redeemed. Blake portrays Satan as having a mild mannered exterior, in addition to a deep rage. He is a powerful spiritual entity and great tormentor.