The intellect is a spiritual power of the human soul which means it operates or functions independently of the body or any bodily organ analogous to angels who are pure spirits and angelic intellects and God himself for humans are made in his image and likeness principally in their spiritual powers of intellect and will. We do not lose the operation of our intellect and will when we die here on earth and our soul leaves the body and goes to meet God in the immediate judgement where we either go immediately to heaven and enjoy God for eternity, purgatory, or hell.
The human soul also has sensory powers like the brute animals and these powers of the soul only operate through the body or bodily organs such as the five external senses. There are also interior sense powers such as the imagination and sensory memory. Although the spiritual powers of intellect and will operate independently of the body as they are spiritual powers, in this life here on earth these spiritual powers of the human soul need the proper operation of the lower sensory powers of the soul and the organs or parts of the body they operate through to function correctly for humans are a composite being of spirit or soul and body. For human beings here on earth, all intellectual knowledge comes through the senses. The process by which the intellect derives its knowledge from the lower sensory powers of the soul is called abstraction.