Carbon-dated to between 1404 and 1438, the manuscript's vellum pages are made from calfskin, not cowhide. Its first confirmed owner was Holy Roman Emperor Rudolf II, who reportedly paid 600 gold ducats for it in the late 16th century—a massive sum. While some early theories linked it to scholar Roger Bacon, the radiocarbon dating proved that impossible. Today, it resides in the Beinecke Rare Book Library at Yale, studied by cryptographers and historians alike, its purpose and language still utte