The soul is the seat of the will and intelligence. St. Thomas Aquinas wrote in the Summa Theologica, I, Question 76. The union of body and soul, Article 8. Whether the soul is in each part of the body?
Objection 4. Further, all the powers of the soul are rooted in the essence of the soul. If, therefore, the whole soul be in each part of the body, it follows that all the powers of the soul are in each part of the body; thus the sight will be in the ear, and hearing in the eye, and this is absurd.
Reply to Objection 4. Some of the powers of the soul are in it according as it exceeds the entire capacity of the body, namely the intellect and the will; whence these powers are not said to be in any part of the body. Other powers are common to the soul and body; wherefore each of these powers need not be wherever the soul is, but only in that part of the body, which is adapted to the operation of such a power.
newadvent.org/summa/1076.htm#article5
Catechism of the Catholic Church, glossary, soul:
The spiritual principle of human beings. The soul is the subject of human consciousness and freedom; soul and body together form one unique human nature. Each human soul is individual and immortal, immediately created by God. The soul does not die with the body, from which it is separated by death, and with which it will be reunited in the final resurrection.