 One of the many uses of the Greek word pathos in ancient philosophy referred, roughly speaking, to what we call emotions. The corresponding Latin terms were passio, affectus or affectio. Medieval theories of emotions were essentially based on ancient sources. The new developments included the discussion of emotions from the point of view of Avicennian faculty psychology, the production of systematic taxonomies particularly in thirteenth-century Aristotelianism, the detailed studies of voluntary and involuntary aspects of emotional reactions, as well as late medieval re-evaluations of the sharp divide between the emotions and the will.