The Protean Ratio

Originating from the observation of the protean meaning of ratio in Eriugena's Periphyseon , the book has the purpose to trace and outline the dynamics of the word used in different philosophical texts from John Scottus Eriugena to Thomas Aquinas. Nine philosophers are taken into consideration: Anselm of Canterbury, Alan of Lille, Gilbert of Poitiers, Peter Abelard, Albertus Magnus, Bernard of Clairvaux, Honorius Augustodunensis, Anselm of Laon, Nicolaus Ambianensis. The meanings of ratio are analyzed according to the broader senses directly related to the kind of philosophy each author represents. The examination of the authors is completed with the crystallization of the notion in its Thomistic articulation. Some meanings absent from the available dictionaries are taken into account.