John Baconthorpe (c.1290-1345/8) was the best-known of the Carmelite scholastics in the Middle Ages. This article is a brief study of his solution to the philosophical problem of how the soul may be wholly present in the human body and present whole and undivided in each part. Baconthorpe’s account is of great interest for a number of reasons. He takes issue with one of his fellow Carmelite masters, alerting us to diversity of opinion within that ‘school’. Furthermore, in using terminology and illustrative analogies drawn from terminist logic and the mathematical sciences, Baconthorpe is an important witness to what has been described as the ‘mathematization’ of philosophy and theology in late medieval England. Finally, study of Baconthorpe’s texts provides further evidence of the emergence of the theme of extension in fourteenth-century thought in which we can discern the roots of modern philosophical debate.