Once Again on Boris Godunov’s Birthday. Heinrich von Logau’s Account

European diplomatic sources from the early 17th century provide us with previously unaccounted for data on Russian history. Thanks to a report by Georg Tectander, a member of Emperor Rudolph II’s mission to Russia, we can now establish the exact date of birth for Boris Godunov. An unpublished manuscript by Tectander’s contemporary and compatriot, Baron Heinrich von Logau, who visited the Tsardom of Russia at the same time, allows us to verify this date as well as to broaden our perspective on everyday life and ceremonial of the royal court, on the Tsar’s personal piety and on the status of the ancient tradition of celebrating birthdays and name days. Moreover, analyzing various calendars used by the diplomats of that era allows us to ascertain that one’s preference for the Gregorian or Julian calendar was not defined by national strategies only but remained a matter of personal choice that was subject to change during one’s life.