Nothing is destroyed by that which makes its perfection. If then the soul is perfected in activity by relinquishing the body and bodily things, its substance cannot fail in being by separation from the body. A natural craving cannot be in vain. Therefore man attains to permanence on the part of his soul, whereby he apprehends existence absolute and for all time.
Intelligible being is more permanent than sensible being.
Therefore the human soul, of which the potential intellect is a part, is indestructible. No form is destroyed except either by the action of the contrary, or by the destruction of the subject wherein it resides, or by the failure of its cause. But the human soul cannot be destroyed by the action of its contrary, for it has no contrary, since by the potential intellect the soul is cognitive and receptive of all contraries. Nor again by the destruction of the subject in which it resides, for it has been shown above that the human soul is a form not dependent on the body for its being. In no way therefore can the human soul be destroyed.