This treatise concerning permissible marriages was published by Augsburg's first printer, Gther Zainer. The author of this text, the Bolognese canon lawyer Johannes Andreae, explained that marriages along direct blood lines ("consanguinity") or as close as third cousins were forbidden. Prohibition also extended to "marriages of affinity" among in-laws. The woodcuts in the form of family "trees" help to clarify the allowable levels and relationships.
06800. Johannes Andreae (d. 1348). Super arboribus consanguinitatis et affinitatis. Augsburg: Günther Zainer, not after 1473.
Giovanni d'Andrea, approximately 1270–1348. , “06800,” Bridwell Library Special Collections Exhibitions, accessed November 29, 2022, https://bridwell.omeka.net/items/show/1780.