In Aristotle’s previous extract, he explained the notion of the soul as a separate entity distinct from the body. This troubled Christian philosophers-theologians for they wanted to re-unite Aristotle’s philosophy with the doctrines of the church. In the “Summa Theologiae” one can see that there are pieces of Aristotelian philosophy like the description of the soul as “the act of the body” that link to Aquinas’ beliefs.
Aristotle however, wasn’t sure if intellect might be distinct from the body. This is where Aquinas argued that the intellectual soul of humans can survive on there are and are indestructible.
The result of this argument somewhat a median between the two stating the Aristotelian approach that our human faculties are “principle involving matter” and a Platonic take better suited for the Christian doctrine of the soul continues to live after death.
Aquinas discusses different aspects of the soul in different ways. The “sensitive” and “nutritive” parts of the soul belong to the human being as a “composite” of soul and body. The more intellectual parts of the soul that set us apart from animals “belong to the soul alone” and “such powers must remain in the soul after the destruction of the body”.
He believes that the sensitive soul depends on the body because in order to demonstrate sensitivity you need to be living and that the intellectual soul carries your knowledge from your life span into your afterlife. Intellect is built throw years and years of human life.
This does not mean that a baby that dies at birth does not have an intellectual soul it just means a man who is elderly in a comparison has a more developed intellectual soul.
In essence, Thomistic thought maintains the intellectual principle of the soul is in concert with the body- yet remains apart from it. With his Aristotelian background, Aquinas ultimately agrees with Aristotle’s hylomorphism, disagreeing with Plato’s dualistic ideals.
Finally, Aquinas asserts that the intellectual soul is inevitably incorruptible because of the obvious nature of form and matter, as defined by Aristotle, whereas the sensitive soul is perishable, as he believes that it is created with man and transferred through his seed, as it is not a perfect self-subsistent substance.