Today is the 504th anniversary of the birth of John Calvin (July 10, 1509). Here are nine things you should know about the French theologian and Reformer.

1. From an early age, Calvin was a precocious student who excelled at Latin and philosophy. He was prepared to go to study of theology in Paris, when his father decided he should become a lawyer. Calvin spend half a decade at the University of Orleans studying law, a subject he did not love.

2. Calvin wrote his magnum opus, The Institutes of the Christian Religion, at the age of 27 (though he updated the work and published new editions throughout his life). The work was intended as an elementary manual for those who wanted to know something about the evangelical faith—“the whole sum of godliness and whatever it is necessary to know about saving doctrine.”

3. Calvin initially had no interest in being a pastor. While headed to Strasbourg he made a detour in Geneva where he met the local church leader William Farel. Calvin said he was only staying one night, but Farel argued that it was God’s will he remain in the city and become a pastor. When Calvin protested that he was a scholar, not a preacher, Farel swore a great oath that God would curse all Calvin’s studies unless he stayed in Geneva. Calvin later said, ““I felt as if God from heaven had laid his mighty hand upon me to stop me in my course—and I was so terror stricken that I did not continue my journey.”

4. Calvin was a stepfather (he married a widow, Idelette, who had two children) but had no surviving children himself. His only son, Jacques, was born prematurely and survived only briefly. When his wife died he wrote to his friend, Viret:

I have been bereaved of the best friend of my life, of one who, if it has been so ordained, would willingly have shared not only my poverty but also my death. During her life she was the faithful helper of my ministry. From her I never experienced the slightest hindrance.

5. During his ministry in Geneva, Calvin preached over two thousand sermons. He preached twice on Sunday and almost every weekday. His sermons lasted more than an hour and he did not use notes.

6. Around 1553, Calvin began an epistolary relationship with Michael Servetus, a Spanish theologian and physician. Servetus wrote several works with anti-trinitarian views so Calvin sent him a copy of his Institutes as a reply. Servetus promptly returned it, thoroughly annotated with critical observations. Calvin wrote to Servetus, “I neither hate you nor despise you; nor do I wish to persecute you; but I would be as hard as iron when I behold you insulting sound doctrine with so great audacity.” In time their correspondence grew more heated until Calvin ended it.

7. In the 1500s, denying the Trinity was a blasphemy that was considered worthy of death throughout Europe. Because he had written books denying the Trinity and denouncing paedobaptism, Servetus was condemned to death by the French Catholic Inquisition. Servetus escaped from prison in Vienne and fled to Italy, but stopped on the way in Geneva. After he attended a sermon by Calvin, Servetus was arrested by the city authorities. French Inquisitors asked that he be extradited to them for execution, but the officials in Geneva refused and brought him before their own heresy trial. Although Calvin believed Servetus deserving of death on account of what he termed as his “execrable blasphemies”, he wanted the Spaniard to be executed by decapitation as a traitor rather than by fire as a heretic. The Geneva council refused his request and burned Servetus at the stake with what was believed to be the last copy of his book chained to his leg.

8. Within Geneva, Calvin’s main concern was the creation of a collège, an institute for the education of children. Although the school was a single institution, it was divided into two parts: a grammar school called the collège and an advanced school called the académie. Within five years there were 1,200 students in the grammar school and 300 in the advanced school. The collège eventually became the Collège Calvin, one of the college preparatory schools of Geneva, while the académie became the University of Geneva.

9. Calvin worked himself nearly to death. As Christian History notes, when he could not walk the couple of hundred yards to church, he was carried in a chair to preach. When the doctor forbade him to go out in the winter air to the lecture room, he crowded the audience into his bedroom and gave lectures there. To those who would urge him to rest, he asked, “What? Would you have the Lord find me idle when he comes?”