 The situation is much more complex, however, when we focus on the human case. If a dualist is someone who thinks that human beings consist in a material body and an immaterial, spiritual mind, then Aquinas clearly qualifies, even if he works very hard to get the result that these two aspects of human nature are unified as a single substance (Bazán 1997; Klima 1997 [2002]; Stump 2003 ch. 6). Although the human soul’s essential role is to actualize a human body, the human soul has a power—its intellect—that operates independently of the body. Aquinas has a variety of much discussed arguments aimed at showing that human thought, given its universal scope and abstract content, cannot be carried out through the brain or any other bodily instrument (ST 1a 75.2, 75.5; Quest. on the Soul 2; Klima 2001; Wood 2020). As a result, the human soul has a unique and puzzling status: it is both the form of a body and “an incorporeal and subsistent principle” (ST 1a 75.2c). From here, Aquinas further argues that the human soul is incorruptible (ST 1a 75.6, Quest. on the Soul 14). For although ordinary subsistent things—material substances—routinely come into and go out of existence, with the corruption of their bodies, a subsistent entity that is not a body has no natural basis for its ceasing to exist. Hence, once God creates a human soul (in coordination with the biological process of sexual reproduction), that soul exists forever.