"Humanity has never submitted to the patient and just, but always only to the great monomaniacs." This wasn't written today with Donald Trump or Vladimir Putin in mind. It was written by Stefan Zweig almost a century ago, surely thinking of Hitler but referring to the fanatic John Calvin (1509-1564), the man who transformed the Protestant Reformation initiated by Luther (a movement for spiritual and religious freedom) into a theocratic dictatorship in Geneva. Educated at the same college as Erasmus and Ignatius of Loyola, Calvin didn't profit much. From persecuted to persecutor, he tortured his society and tortured himself: he slept a maximum of four hours and ate only a meager meal a day; no distractions, no relaxation, no pleasure. The ascetic, says Zweig, "is the most dangerous type of despot."