One of Milescu's tasks was to reinforce the legitimacy of the Romanov Dynasty. To this end, he asserted that the Tsar was a successor to both the Roman and Byzantine emperors. In "Vasiliologion" ("Book of Rulers", 1674), he wrote that tsarist rule was derived from God, whose representative on earth was the Tsar. The work included short biographies of famous rulers, culminating with Michael Romanov and Aleksey, but also including Ivan the Terrible, Dmitry Donskoy, Alexander Nevsky, Byzantine emperors Constantine and Theodosius, and Augustus and Julius Caesar from Rome. Significantly, he included the feeble-minded Feodor Ivanovich, whose reign was considerably less illustrious, but who had to be mentioned in order to demonstrate dynastic continuity.