From then on, the identity of this man was thoroughly discussed, mainly because no one ever saw his face, hidden by a black velvet mask (not iron as later claimed). Voltaire said he was a brother to King Louis XIV.
Much later, Alexandre Dumas discussed many possible identities for the prisoner in chapter seven of Une année à Florence.
He developed the hypothesis of the King's twin in the novel The Vicomte de Bragelonne with such mastership that the myth of the Iron Mask became associated with his name. In the English translations this large volume is usually subdivided into three, four or even five individual books, with the final volume titled The Man in the Iron Mask.