The terms “Grand Duchy of Lithuania” and “Lithuania” are used interchangeably in the book, despite the historical context distinguishing them. In sixteenth‐century discourse, the term “Lithuanian” had both political and ethnic significance. I have therefore sought to present a thorough and comprehensive account of the early stages of the Protestant movement as it unfolded within the Grand Duchy of Lithuania, encompassing the partly Lithuanian‐populated territory within Ducal Prussia.
I have used established English spellings for the principal cities and places of Lithuania and Poland such as Vilnius and Warsaw, as well as localities in the Grand Duchy of Lithuania, which is now part of modern‐day Belarus, such as Nesvizh. All other Lithuanian place names are written in established Lithuanian spellings, and Polish localities are written in Polish spellings.
I adhere to various principles for the spelling of personal names. I generally use Polish names in Polish spelling and Lithuanian names in Lithuanian spelling. Nevertheless, for individuals like Symon Budny, Peter Gonesius, and Andreas Volanus, who were primarily associated with the Grand Duchy of Lithuania but had various origins, I use the spellings that are most widely used in the scholarly literature. I disregard the established Polish spelling for representatives of Lithuanian aristocratic families and instead use Lithuanian spelling, such as Mikalojus Radvila rather than Mikołaj Radziwiłł and Paulius Alšėniškis rather than Paweł Holszański. I include a Polish spelling when they are mentioned for the first time or provide Latin versions for some Lithuanian authors. In some instances, I use a form that matches both in Latin and Polish, chosen for the convenience of English readers, as exemplified by Nicolaus Pac.