Arguably, the most significant event of Cleon's rule occurred in 12,020 GE, when the young mathematician Hari Seldon came to Trantor and revealed that psychohistory was a theoretical possibility. Cleon I’s reign represented a curious interval of quiet between troubled times. This is undoubtedly due to the skills of his chief of staff, Eto Demerzel. Cleon would never have learned of this development by his own efforts; insulated from the Galaxy and confined to the Imperial Palace's grounds, he relied upon Demerzel to conduct the Machiavellian maneuvers required to keep the Empire functioning. Demerzel became aware that Seldon could possibly develop a mathematical method for predicting future history, and he (indirectly) informed the Emperor, who took an immediate interest in the matter. While Cleon was content to use Seldon as a source of self-fulfilling prophecies—a tool to prevent unrest—Demerzel had come to believe that the Empire itself was dying, and that only an honest investigation could prevent its fall or at least minimize that fall's effects. Therefore, Demerzel took steps to promote Seldon's development of his infant science.