In Hell, Dante and Virgil meet those guilty of simony (buying or selling ecclesiastical preferment). Like all simoniacs, Pope Nicholas III is punished by being suspended head downwards in a well of fire.
The paper is watermarked ‘W ELGAR 1794’, the year it was produced. It was then bound into book form. The parallel lines in the paper show it is ‘laid’. This means it has more texture than Blake generally used, but the weight of the book would have flattened it. The two sides of the paper have different textures: Blake used both sides for his illustrations.