In The Marriage of Heaven and Hell Blake has his mind continually upon the Swedenborgian system, in part as the ground of his own, in part as that from which he wishes to define his own points of difference. The central claim of Swedenborg's teaching is that a Last Judgment has been passed in the heavens upon all the Churches that had existed until the beginning of the New Age. Isaiah 34:9-13 describes the divine vengeance that destroyed the land of Idumea (Edom), turning a heaven into a hell: And the streams thereof shall be turned into pitch, and the dust thereof into brimstone, and the land thereof shall become burning pitch. Ariosto's first orc is a sea monster based upon the ravisher of maidens turned to stone by Perseus; the second resembles Homer's Cyclops, but he too keeps in his cave not shipwrecked sailors but maidens: both share with Blake's demon sexual passion.