Having made clear the conception of soul generally and its relation to the body, he next proceeds to treat of the three kinds of soul. The highest of these is the rational soul, which is in the horizon of the Intelligence and arises from its shadow. It is in virtue of this soul that man is a rational being, discriminating, receptive of wisdom, distinguishing between good and evil, between things desirable and undesirable, approaching the meritorious and departing from wrong. For this he receives reward and punishment, because he knows what he is doing and that retribution follows upon his conduct.
Next to the rational soul is the animal soul, which arises from the shadow of the former. Being far removed from the light of Intelligence, the animal soul is dark and obscure. She has no knowledge or discrimination, but only a dim notion of truth, and judges by appearance only and not according to reality. Of its properties are sense perception, motion and change in place. For this reason the animals are fierce and violent, endeavoring to rule, but without clear knowledge and discrimination, like the lion who wants to rule over the other beasts, without having a clear consciousness of what he is doing. A proof that the animals have only dim notions of things is that a thirsty ass coming to the river will fly from his own shadow in the water, though he needs the latter for preserving his life, whereas he will not hesitate to approach a lion, who will devour him. Therefore the animals receive no reward or punishment (this in opposition to the Mutakallimun) because they do not know what to do so as to be rewarded, or what to avoid, in order not to be punished.
The vegetative soul proceeds from the shadow of the animal soul. She is still further removed from the light of Intelligence, and still more weighed down with shadow. She has no sense perception or motion. She is next to earth and is characterized by the powers of reproduction, growth, nutrition, and the production of buds and flowers, odors and tastes.
Next to the soul comes the Sphere (the heaven), which arises in the horizon and shadow of the vegetative soul. The Sphere is superior to corporeal substances, being itself not body, but the matter of body. Unlike the material elements, which suffer change and diminution through the things which arise out of them as well as through the return of the bodies of plants and animals back to them as their elements, the spiritual substances (and also the sphere) do not suffer any increase or diminution through the production of things out of them. For plants and animals are produced from the elements through a celestial power which God placed in nature effecting generation and decay in order that this world of genesis and dissolution should exist. But the splendor of the higher substances, viz., the three souls, suffers no change on account of the things coming from them because that which is produced by them issues from the _shadow_ of their splendor and not from the essence of the splendor itself. And it is clear that the splendor of a thing in its essence is brighter than the splendor of its shadow, viz., that which comes from it. Hence the splendor of the vegetative soul is undoubtedly brighter than that of the sphere, which comes from its shadow. The latter becomes rigid and assumes a covering, thickness and corporeality so that it can be perceived by sight. But no other of the senses can perceive it because, although corporeal, it is near to the higher substances in form and nobility, and is moved by a perfect and complete motion, motion in a circle, which is more perfect than other motions and not subject to influence and change. Hence there is no increase or diminution in it, no beginning or end, and this on account of the simplicity, spirituality and permanence of that which moves it. The Intelligence pours of her splendor upon it, and of the light of her knowledge, and the sphere becomes intelligent and rational, and knows, without investigation or reflection, the lordship of its Creator, and that he should be praised and glorified without intermission. For this reason the Creator assigned to the Sphere a high degree from which it cannot be removed, and gave it charge of the production of time and the four seasons of the year, and the month and the day and the hour, and made it ruler of the production of perishable things in this world of generation and dissolution, so that the upper souls may find bodies to apprehend, to clothe with their light, and to make visible in them their activities according to the determination of God.