John Calvin never meant to be any of this. He was a lawyer's son from Noyon in Picardy, born in 1509, given a chaplaincy at the cathedral when he was twelve because that was how a careful father provided for a clever boy, and set to civil law at Orleans because his father judged it the safer road. He was good at it. He was better at Greek and Latin letters, and his first book, at twenty-three, was a commentary on Seneca: a young humanist's calling card, not a reformer's manifesto.

Then something happened that he would describe, twenty-five years later, in six words: "God by a sudden conversion subdued and brought my mind to a teachable frame." He says he was too obstinately fixed in the old ways to be pulled out of them gently, so he was not pulled gently. And he says that within a year, before he thought himself anything but a beginner, people who wanted purer doctrine were coming to him to learn.

That was inconvenient, because John Calvin wanted a corner and a desk. He says so plainly. He was bashful, he loved the shade, and he kept looking for somewhere quiet to be unknown; and every retreat he found, he wrote, turned into a public school.

Meanwhile France was burning its evangelicals. His friend Nicolas Cop, newly Rector of the University of Paris, gave an address on All Saints' Day 1533 that sounded far too much like the new teaching, and both men fled. Calvin ended up in Basel, and there, an exile at twenty-six, he wrote a small book of six chapters explaining what these hunted people actually believed, and addressed it to King Francis I of France, who was doing the hunting. He told the king that the book had begun as nothing grand: "My intention was only to furnish a kind of rudiments, by which those who feel some interest in religion might be trained to true godliness." Then he made his case, and in the middle of it came the sentence that shows what the book really was: "For this hope some of us are in bonds, some beaten with rods, some made a gazing-stock, some proscribed, some most cruelly tortured, some obliged to flee." That is the Institutes of the Christian Religion. Not a system first. A petition for the lives of his friends.

And then Geneva. In the summer of 1536 a war had closed the direct road, and Calvin, detouring toward Strasbourg and his quiet desk, stopped in Geneva for a single night. Someone recognized him. Word reached Guillaume Farel, who was leading the city's raw new Reformation and needed help badly, and Farel came and asked. Calvin said no. He explained about the private studies. So Farel, in Calvin's own telling, "proceeded to utter an imprecation that God would curse my retirement, and the tranquillity of the studies which I sought, if I should withdraw and refuse to give assistance, when the necessity was so urgent." Calvin was, he says, so stricken with terror that he unpacked. He felt it "as if God had from heaven laid his mighty hand upon me to arrest me."

He got two years before the city threw him out. He got three years at Strasbourg with Martin Bucer, the happiest of his life by his own account, pastoring French refugees, and it was Bucer who found him a wife: Idelette de Bure, a widow, whom he married in August 1540. Then Geneva changed its mind and asked him back, and he went back, unwillingly, to the city that had expelled him, and stayed twenty-three years. He was not its ruler. He was a foreigner without citizenship until 1559, five years before he died. He was often opposed and sometimes beaten.

Those years cost him. An infant son, born and dead in 1542, of whom he said: "God has given me a little son, and taken him away; but I have myriads of children in the whole Christian world." Idelette, dead in the spring of 1549 after nine years, "the excellent companion of my life," "the ever-faithful assistant of my ministry." He never married again. And there was a thing done in Geneva in 1553 that he never explained away and that this page will not explain away either: Michael Servetus, who had denied the Trinity, was arrested at Calvin's instigation, tried by the city council, and burned at Champel on 27 October. Calvin sought the arrest and supported the sentence. He wrote to Farel hoping the severity of the punishment might be lessened, and Farel wrote back rebuking him for the tenderness of it. That is the record. It is not a rumour, and it is not smaller than it looks.

He preached, meanwhile, more than two thousand times, extempore, without notes, and never wrote a word of it down; the sermons survive only because refugees hired a man named Denis Raguenier to sit and take them in shorthand. He founded a school in 1559 that opened with some nine hundred students and is a university still.

At the end he was fifty-four and could hardly breathe. On 28 April 1564 he called the ministers of Geneva to his room and told them, of the years when the city had been chaos and men had heaped indignities on him, "the Lord our God so confirmed me, who am by no means naturally bold, (I say what is true,) that I succumbed to none of their attempts." Then he apologized. If, while ill, they had experienced any degree of peevishness from him, he begged their pardon, and thanked them. He shook each man's hand. Beza, who was there, wrote that they left him with eyes certainly not unmoistened. In May he wrote to Farel, then seventy-nine, telling him not to make the journey. Farel made it anyway, sat with him, and went home the next day.

Three days before that letter, Calvin had dictated his will to a notary, who wrote it down word for word. It is the will of a man who had spent his whole life explaining what God requires, and it does not explain anything. It asks. "I trust to no other security for my salvation than this, and this only, viz., that as God is the Father of mercy, he will show himself such a Father to me, who acknowledge myself to be a miserable sinner."

He died on the evening of 27 May 1564. The city's own register entered it in the plainest words a clerk could find: Ce iourd'huy environ huit heures du soir le sp. Ian Calvin est allé à Dieu, this day, about eight in the evening, the honourable Jean Calvin went to God. Beza, at the bedside, said he was sensible almost to the last breath and looked much more like one sleeping than dead. The next day they buried him at Plainpalais with no stone, because he had told them to, and no one now knows the spot. He had spent his life saying that our wisdom is the knowledge of God and of ourselves, and that we are not our own; and when it came to his own grave he was consistent to the end, and let it be lost.