The Lutheran theologian and polemicist Matthias Flacius Illyricus (1520-75) organized an unprecedented collaborative project to write an encyclopedic Protestant church history, known as the Magdeburg Centuries (1559-74). At the planning stage in 1556, Flacius and his colleagues consulted with the Flemish jurist FranÁois Baudouin (1520-73). This article shows how, in this correspondence, ecclesiastical history became the workshop where legal and theological humanism met and interacted over issues of historical methodology. Two innovations are traced through the correspondence and into the finished (...) history: Flacius's organization of the material by commonplaces. (shrink)