According to tradition, in 1517, Martin Luther displayed 95 theses on the doors of the chapel of the castle of Wittenberg. The idea was to start a theological controversy on the legitimacy of the trade of “indulgences”, then very active as money had to be found to build the dome of Saint Peter Cathedral in Rome. The impact was far greater than anticipated. The posting of the these became the founding event of the Protestant Reformation the 500^th anniversary of which is celebrated in 2017.