He obeyed, and bade farewell to his congregation in a sermon full of strength and eloquence.
But the withdrawal of Savonarola, so far from calming the ferment, had increased it: there was talk about his prophecies being fulfilled; and some zealots, more ardent than their mastery added miracle to inspiration, and loudly proclaimed that Savonarola had offered to go down into the vaults of the cathedral with his antagonist, and there bring a dead man to life again, to prove that his doctrine was true, promising to declare himself vanquished if the miracle were performed by his adversary.

These rumours reached the ears of Fra Francesco, and as he was a man of warm blood, who counted his own life as nothing if it might be spent to help his cause, he declared in all humility that he felt he was too great a sinner for God to work a miracle in his behalf; but he proposed another challenge: he would try with Savonarola the ordeal of fire.

He knew, he said, that he must perish, but at least he should perish avenging the cause of religion, since he was certain to involve in his destruction the tempter who plunged so many souls beside his own into eternal damnation.
The proposition made by Fra Francesco was taken to Savanarola; but as he had never proposed the earlier challenge, he hesitated to accept the second; hereupon his disciple, Fra Domenico Bonvicini, more confident than his master in his own power, declared himself ready to accept the trial by fire in his stead; so certain was he that God would perform a miracle by the intercession of Savonarola, His prophet.
Instantly the report spread through Florence that the mortal challenge was accepted; Savonarola's partisans, all men of the strongest convictions, felt no doubt as to the success of their cause.

His enemies were enchanted at the thought of the heretic giving himself to the flames; and the indifferent saw in the ordeal a spectacle of real and terrible interest.
But the devotion of Fra Bonvicini of Pescia was not what Fra Francesco was reckoning with.

He was willing, no doubt, to die a terrible death, but on condition that Savanarola died with him.