He said Voltaire was so prolific because he was popular in his own time. He called him “the first-ever European celebrity.”

“He was famous in London. He was famous in Warsaw,” he said. “And there were translations in Philadelphia in his lifetime.”

Philadelphia was where a more perfect union was formed, and founders like Benjamin Franklin knew Voltaire’s writings. (Franklin later knew Voltaire himself, when Franklin was sent to Paris as the first ambassador of the new nation. Voltaire, who was dying, said, in English, the words “God” and “liberty” to Franklin and his grandson when they visited. “It was completely banal,” Professor Cronk said after recounting the episode, “but it had the ring of brilliance.”)

Voltaire faced the problem that celebrities like Taylor Swift and Justin Bieber face nowadays. “You have to give the public material,” Professor Cronk said with another laugh, this one about the idea of mentioning Voltaire in the same breath as the other two. “He produced anecdotes. It is the way he managed his celebrity. He had to be in front of his public.”

And sometimes, Professor Cronk said, Voltaire misled his public. “One doesn’t want to say that he lies,” he said. “But you can say contradictory things to get them listening to you.”

Consider the most basic of facts, the date of Voltaire’s birth.

He was christened in Paris on Nov. 22, 1694. “That is the one sure fact we have,” Professor Cronk said.