Action in Medieval Commentaries on "De sensu et sensato"

The present essay discusses perception as action of both the object and of the soul in medieval Latin commentaries on Aristotle’s "De sensu et sensato". Beginning with the Aristotelian principle that sensible qualities are defined by their ability to act on the external senses so as to engender sensations, we first explore medieval positions concerning the thorny issue of whether sensible qualities can remain active even when they are present in extremely small quantities of matter. Then we turn to the activity of the soul, which was discussed in relation to the ability to perceive several perceptual qualities simultaneously. Many medieval authors emphasised that powers of the soul have an active role in the process of perception, as they form judgements and pay attention to the objects of the senses. The final section of the essay is dedicated to a case study of Walter Burley. New evidence coming from manuscript research suggests that Burley may have been one of the medieval Latin thinkers who considered the concept of action in detail while commenting on "De sensu". In particular, we discuss the hypothesis that Burley may have authored a question commentary on "De sensu" which is preserved in ms. London, British Library, Add. 18630, ff. 54r-67v and attributed to him in the manuscript. Although the authorship of the text remains uncertain, we show that this commentary is identical with a hitherto anonymous "De sensu" commentary preserved in ms. Oxford, Merton College, 276, ff. 1ra-8vb. Moreover, we claim that this commentary has strong ties with another question commentary on "De sensu" that has been attributed to Burley in secondary literature and we present some preliminary observations concerning the complex relation of both works with Burley’s literal commentary on "De sensu". We argue that these commentaries bear witness to the main alternative positions concerning both issues discussed in this essay. Therefore, if Burley wrote all of them, his case would represent a remarkable example of the liveliness of the debate about the active aspects of perception within the medieval Latin "De sensu" commentary tradition.