Abstract
A prominent argument for the immateriality of the soul is the so-called "Achilles Argument", which relies on the claim that the soul is simple or indivisible. It was not widely used in the Aristotelian tradition, however. But a version of the argument played a crucial role in Suárez’s contention that a human being contains only one unitary soul. On an alternative view that was widespread at the time, living substances may contain several souls, such as a sensitive and a rational soul in the case of human beings. Suárez holds that the powers of the soul are really distinct from each other and from the soul itself. At the same time, the actions of the different powers of the soul influence each other, as when a loud noise distracts me from doing philosophy or when my intellect relies on my imagination for mental images. Suárez argues that this interaction between powers requires that they are all are "rooted" [radicatae] in one single soul.