Thomas Aquinas, Compendium of Theology

The body is for the soul, as matter is for form and a tool for the craftsman. At the resurrection, therefore, when the life we have been speaking of is attained, God will join to the soul a body such as befits the beatitude of the soul; for whatever exists for the sake of an end, must be duly disposed in accord with the demands of the end. A soul that has arrived at the peak of intellectual activity cannot appropriately have a body that would in any way prove an impediment or a burden to it. But the human body, by reason of its corruptibility, does obstruct and slow down the soul, so that the soul can neither devote itself to uninterrupted contemplation nor reach the heights of contemplation.

This is why men are able to grasp divine truths more readily when they rise above the bodily senses. And so prophetic revelations are made to men when asleep, or when they are lost in mental ecstasy, as we read in Numbers 12:6: "If there be among you a prophet of the Lord, I will appear to him in a vision, or I will speak to him in a dream." Therefore the bodies of risen saints will not be corruptible and will not burden down the soul, as they do now. On the contrary, they will be incorruptible and will be wholly obedient to the soul, so as not to resist it in any way whatever.