The famous Bolognese authority on canon law, Johannes Andreae, wrote
several treatises in regard to relationships considered too close for marriage.
These were often illustrated with tree diagrams to facilitate understanding of
the concepts of consanguinity, or blood relationships, affinity, or
relationships by marriage, and spiritual relationships, those created through
sacramental duties such as that of godparent. In this manuscript, the Arbor
affinitatis (f. 7v) shows a person in an Italianate hat above the tree who
may represent the author. The Arbor consanguinitatis (f. 3v) shows a pope
above the tree, undoubtedly Innocent III. The work was often found bound after
early printed copies of the great collections of canon law. The Burke Library
has copies so bound, but this one came to New York with the library of Leander
van Ess unbound, as it remains today.