Hurrying me into a musician's gallery, which overlooked the chamber in which the incantations were about to take place, the sorcerer showed me a strange instrument, compounded of lenses set in a black box in which burned a small lamp. "Fear not, Benvenuto," he whispered, seeing that I hesitated, "but manipulate this machine as I will now show you, placing from time to time these slips of painted glass in front of the lamp, and when I shall call upon the name of the arch fiend Beelzebub, be careful to introduce the copy of the portrait of the Duke which you have just made for Monna Afra." He then made some cabalistic signs upon my forehead and bidding me be of stout heart descended to the main floor of the room, which was but dimly lighted by the flames of a brazier. I could see, however, that around the light were grouped the Duchess Margaret, Monna Afra and Ottavio, who suspecting some design against his mistress, had insisted on accompanying her. Around these three the necromancer now traced upon the floor a magic circle; entering it and directing Margaret to keep her eyes fixed on the wall opposite to the little gallery where I stood, he invoked with a loud voice the demons Soracil, Sathiel, and Ammon dwellers in the moon, bidding them appear with all their legions. As I had previously witnessed a similar conjuration by which another necromancer had filled the tiers of the Colosseum with innumerable legions of devils, the horrible fear which I had experienced on that occasion returned in so lively a manner that my hands trembled so that I could scarcely perform the rites assigned to me. I had hardly introduced the first slip of glass when Ottavio cried out that the house was on fire and endeavoured to drag the Duchess from the circle, but the necromancer held him firmly and commanded him on his life not to stir as the demons were gathering in force. Having placed the next slip of glass in its place I myself perceived them, horrid creatures of gigantic stature clutching at their victims. Thus the ceremony proceeded, the enchanter uttering strange sentences in the Hebrew language, while Monna Afra shrieked and howled in blood-curdling tones. Ottavio also was well-nigh bereft of his senses with fear, and flinging his arms about the Duchess cried to the fiends to take him to hell, but to spare his beloved lady. At this point, Margaret, who was strangely unafraid, repeated after the necromancer these words: "I conjure thee, Beelzebub, Prince of Darkness, to reveal to me the likeness of my lord and husband, and renouncing all others I promise to be true to him throughout all eternity." This was my cue, but fumbling in the casket for the portrait of Duke Alessandro I inadvertently introduced into the throat of the infernal machine not that bit of glass but the one on which I had painted the likeness of Ottavio.