As for the rest Ibn Sina makes every endeavour to conform to the popular belief. Everything exists, he says, through God’s appointment, both the Good and the Evil, but it is only the former that meets with his glad approval. Evil is either a non-existent thing, or,—in so far as it proceeds from God,—an accidental thing. Suppose that He, to avoid the evils which of necessity cling to the world, had kept it from coming into being,—that would have been the greatest evil of all. The world could not be better or more beautiful than it actually is. The Divine Providence, administered as it is by the Souls of the Heavens, is found in the world’s fair order. God and the pure Spirits know the Universal only, and therefore are unable to attend to the Particular; but the Souls of the celestial Spheres, to whose charge falls the representation of what is individual, and through whom Spirit acts upon Body, render it possible to admit a providential care for the individual thing and the individual person, and to account for revelation, and so on. Farther, the sudden rise and disappearance of substances (Creation and Annihilation), in contrast to the constant movement,—that is, the gradual passing of the Possible into the Actual,—seem to Ibn Sina to indicate nothing impossible. In general, there is a predominant want of clearness in his views regarding the relation of the forms of Existence,—Spirit and Body, Form and Matter, Substance and Accident. A place at all events is left for Miracle. In passionate forms of excitement in the Soul, which often generate in ourselves great heat or cold, we have, according to Ibn Sina, phenomena analogous to miraculous effects produced by the World-Soul, although it usually follows the course of Nature. Our philosopher himself, however, makes a very moderate use of any of these possibilities. Astrology and Alchemy he combated on quite rational grounds; and yet soon after his death astrological poems were attributed to him; and in Turkish Romance-Literature he appears as a magician, of course to represent an ancient Mystic. Ibn Sina’s theory of Physics rests entirely on the assumption that a body can cause nothing. That which causes,—is in every case a Power, a Form, or a Soul, the Spirit operating through such instrumentality. In the realm of the Physical there are accordingly countless Powers, the chief grades of which, from the lower to the higher, are—the Forces of Nature, the Energies of Plants and Animals, Human Souls and World-Souls. 5. Farabi was above all things interested in pure Reason: he loved Thinking for its own sake, Ibn Sina, on the other hand, is concerned throughout with the Soul. In his Medicine it is man’s Body which he looks to; and similarly, in his Philosophy his eyes are fixed on man’s Soul. The very name of his great Philosophical Encyclopaedia is—‘The Healing’ (that is—of the Soul). His system centres in Psychology.