To return from our digression, the three souls, Ibn Zaddik tells us, are spiritual powers; every one of them is a substance by itself of benefit to the body. The rational soul gets the name soul primarily, and the others get it from the rational soul. The _Intellect_ is called soul because the rational soul and the Intellect have a common matter. And hence when the soul is perfected it becomes intellect. This is why the rational soul is called potential intellect. The only difference between them is one of degree and excellence. The world of Intellect is superior, and its matter is the pure light, Intellect in which there is no ignorance, because it comes from God without any intermediate agency. Here we see just a touch of the Neo-Platonic doctrine of emanation, of which the Universal Intellect is the first. But it is considerably toned down and not continued down the series as in Plotinus or the Brethren of Purity. The accidents of the soul are spiritual like the soul itself. They are, knowledge, kindness, goodness, justice, and other similar qualities. Ignorance, wrong, evil, and so on, are not the opposites of those mentioned above, and were not created with the soul like the others. They are merely the absence of the positive qualities mentioned before, as darkness is the absence of light. God did not create any defect, nor did he desire it. Evil is simply the result of the incapacity of a given thing to receive a particular good. If all things were capable of receiving goods equally, all things would be one thing, and the Creator and his creatures would be likewise one. This was not God's purpose. There is a tacit opposition to the Mutakallimun in Ibn Zaddik's arguments against the view that the soul is an accident, as well as in his statement in the preceding paragraph that the bad qualities and evil generally are not opposites of the good qualities and good respectively, but that they are merely privations, absences, and hence not created by God. This is a Neo-Platonic doctrine. Pseudo-Bahya, we have seen (p. 108 f.), and Abraham bar Hiyya (p. 123 f.) adopt the Kalamistic view in the latter point, and solve the problem of evil differently. The function of the rational soul is knowledge. The rational soul investigates the unknown and comprehends it. It derives general rules, makes premises and infers one thing from another. Man alone has this privilege. It is in virtue of the rational soul that we have been given commandments and prohibitions, and become liable to reward and punishment. Brute animals have no commandments, because they have no reason. The soul has reason only potentially, and man makes it actual by study. If the reason were actual originally in the soul, there would be no difference between the soul's condition in its own world and in this one; and the purpose of man, which is that he may learn in order to choose the right way and win salvation, would have no meaning.