At the outbreak of the Revolution Fontaines, then aged twenty, was a violent Jacobin; during the Reign of Terror he cast in his lot with Eulogius Schneider, and was one of the most eager of that man's followers in denouncing the clergy, closing churches, plundering Strasburg Cathedral, &c. He held orations in the temples of Reason, got himself appointed a Protestant pastor, married, and behaved in such a scandalous manner that he was compelled to give up his charge. Nevertheless, when the reaction against the Revolution set in, he received another call, as representative of the extremest Pietism, and soon gained a great reputation as an exorciser of evil spirits. When it came out that he had managed in three years (1801-4) to make away with almost all the means of his congregation, he had to retire into obscurity for a time. In 1805 he received a call to Markirch. There, two years later, he took Marie Kummer into his house. This woman, though she was a simple vagrant, and had changed her religion several times, was held in great reverence by the Pietists. A certain Pastor Hiller consecrated her to be the bride of Jesus. In the course of time she bore this same pastor a son, who was destined, they declared, to become the witness mentioned in the third verse of the eleventh chapter of the Book of Revelation. The worldly-minded civil authorities none the less condemned Marie to the pillory and a term of imprisonment. When she came out of prison she proclaimed the end of the world to be at hand, and advised a general emigration of believers to the Holy Land. She actually persuaded a number of foolish persons to set out with her for Jerusalem, and to entrust her with the travelling funds; but when they reached Vienna she was taken into custody. After a term of imprisonment there she went back to Alsace. The comet of 1807 furnished her with a pretext for sensational prophecies of plague, famine, and war, and on hearing the report of the arrival of the Russian baroness she had a vision, in which that lady's high destiny was revealed to her.