How did Thomas Aquinas describe the relationship between the human soul and the body?

In the theological and philosophical system of St. Thomas Aquinas, the relationship between the human soul and the body is defined by the Aristotelian concept of the soul as the "form" of the body.12

Aquinas taught that the human being is a composite of two intrinsic principles: the body, which serves as the matter, and the soul, which serves as the substantial form that makes a human being what they are. Unlike Aristotle, who generally viewed form as inseparable from matter, Aquinas characterized the human soul as a "unique subsistent form".12

This distinction is central to Thomism: while the soul is substantially united with matter to constitute human nature, it is also capable of existing independently of the body. Consequently, Aquinas argued that the soul is incorruptible and survives the death of the body, a position he maintained could be strictly demonstrated. By situating the human being at the juncture of the corporeal and spiritual universes, Aquinas sought to affirm both the reality of the physical world and the transcendence of the human spirit.2341