Voltaire was imprisoned in the Bastille, in 1717. According to him, this prisoner was an older brother of the King. In 1751, he published his work A century of Louis XIV, where he spends a section detailing the story of the man with the iron mask. According to Voltaire, the man was imprisoned in 1661, after the death of Cardinal Mazarin. It is possible that most of what is known today was an invention of Voltaire, who used this man to give an example of how bad an absolute ruler could be.