Heinrich Bullinger (1504–1575) stands as one of the most influential figures of the European Reformation. His vast correspondence network spanned from Klyetsk (Belarus) in the east to La Rochelle in western France, from Rome in the south to Kolding (Denmark) in the north, encompassing scholars, theologians, scientists, kings, and counts. This extensive corpus, comprising over 12,000 preserved letters (2,813 by Bullinger himself), covers a wide range of topics from worldly news and theological debates to family matters.