Black Magic

Black Magic begins with this ominous first line: 'In the large room of a house in a certain quiet city in Flanders, a man was guilding a devil'. That person is Dirk Renswoude, a craftsman and loner of noble birth who has been mistreated in some unspecified way by his family. He meets Thierry, a young scholar on his way to study at the university at Basle and they soon discover that they have a shared fascination with the black arts.
However, Thierry is initially cautious and afraid of blasphemy, whilst Dirk is ambitious to be "as great as the Master we serve can make his followers" and thirst for power. Dirk leads them on to experiments with mystic circles drawn on the floor in chalk, the chanting of arcane incantations and the evocation of grotesque, demonic visions writhing in the speculum. Thierry still wavers, but when their experiments lead to murder the die is cast for both of them.

One of the best gothic novels ever written!