‘“The other coach belonged to a rival family among the Monti, and it seemed an old beggar had stumbled in the street, causing the horses to shy and swerve. The enraged occupant, a brutish young nobleman, had leapt out, seized a cudgel from one of his guards and was beating the beggar most savagely.

‘“Without pausing, Caterina also jumped out into the mud and slime, ruining her silken slippers, and screamed at the man to stop. He looked up and she saw he was one of those young nobles her father had wished her to marry. He, seeing the shield of the Petrucci on her coach door, ceased what he was doing and climbed back into his carriage.

‘“The girl squatted in the mud and held the torso of the filthy old beggar, but he was dying from his beating. Though such people must have been alive with parasites, stinking of mud and excrement, she held him in her arms as he died. The legend is that as she looked down into the exhausted, pain-racked face, smeared with mud and blood, she thought she saw the face of the dying Christ. Our old chronicler records that he whispered as he died, ‘Look after my people.’

‘“We will never know what really happened that day, for no eyewitnesses ever spoke of it. We just have the words of an old priest writing in a lonely monastic cell years later. But whatever happened, it changed her life. She went home and, in the courtyard of the palazzo, burned her entire wardrobe. She told her father she wished to renounce the world and enter a nunnery. He would have none of it and expressly forbade her.

‘“Defying his will, something unheard of in those days, she toured the nunneries and convents of the city seeking admission as a novice. But messengers from her father had gone ahead of her and she was refused by them all. They knew the residual power of the Petrucci.

‘“If her father thought that would stop her, he was wrong. She stole from the family treasury her very own dowry and, after negotiating secretly with a rival Monte, secured a long lease on a certain courtyard. It was not much; it belonged to and abutted the towering walls of the monastery of Santa Cecilia. The monks had no use for it: about twenty metres wide by thirty metres long, with a cloister running down one side and lying in the shadow of the high walls of stone.

‘“To ensure that separation would be total, the Father Superior installed a great timber door of oaken beams in the only arch that led from the monastery into the courtyard and sealed it with heavy bolts.