Ubertino of Casale stands at the crossroads of the European mystical tradition. Fascinated by the models of the mystics of the end of the century, starting from Angela of Foligno, he engaged with the problems and contradictions posed by Francis of Assisi's legacy. At the core of his awareness is the Arbor Vitae Crucifixae, but its manuscript tradition and textual stages are only partly known and although it is a crucial work a critical edition has yet to be made. In 2013 the Edizione Nazionale dei Testi Mediolatini d'Italia launched a project to prepare one and the Fondazione Ezio Franceschini is pleased to host a public occasion for the group that has been established, to support its work. The solution to the problem posed by the edition of the Arbor involves the decisive historiographical acquisition regarding the relation between Ubertino and the mystic, and for this reason the context of the Seminars on History and Mystical Theology named for Claudio Leonardi appears to be the ideal setting for this workshop.