1. Abū Naṣr said: The principles that constitute bodies and their accidents — which are of six sorts — are of six major rankings, and each ranking embraces one of the sorts. The first cause is in the first ranking; the secondary causes are in the second ranking; the active intellect is in the third ranking; the soul is in the fourth ranking; form is in the fifth ranking; material is in the sixth ranking. What is in the first ranking cannot be many; rather, it is only one, unique. What is in each of the rest of the rankings is many. Three of them are neither bodies nor in bodies — namely, the first cause, the secondary ones, and the active intellect. And three are in bodies even though they are not themselves bodies — namely, soul, form, and material. There are six kinds of bodies: the heavenly body, the rational animal, nonrational animals, plants, minerals, and the four elements. The whole brought together from these six kinds of bodies is the world.
2. The first [cause] is what ought to be believed to be the deity. It is the proximate cause for the existence of the secondary [causes] and for the existence of the active intellect. The secondary ones are the causes for the existence of the heavenly bodies; from them, these bodies attain their substances; and from each of the secondary ones results the existence of every one of the heavenly bodies. From the highest of the secondary [causes] in rank results the existence of the first heavens, and from the lowest of them results the existence of the sphere of the moon. From each of the intermediate ones results the existence of each of the planets that are between these two. The secondary [causes] are as numerous as the heavenly bodies; and the secondary [causes] ought to be said to be spiritual existents, angels, and the like.
3. The activity of the active intellect is looking out for the rational animal and seeking for it to obtain the ultimate ranking of perfection that a human being can obtain, namely, ultimate happiness — which is for a human being to reach the ranking of the active intellect. Now that comes about only by attaining separation from bodies, not having need of anything lesser — not body, material, nor accident — for subsistence, and by always remaining at that perfection.
While the active intellect is one in essence, its rank also embraces those rational animals who have become transcendent and achieved happiness. Of the active intellect, it ought to be said that it is the trustworthy spirit and the holy spirit. It is called by names resembling these two, while its ranking is called kingship and names resembling that.
4. The principles in the ranking of the soul are many. Among them are the souls of the heavenly bodies, the souls of the rational animal, and the souls of the nonrational animals. Those belonging to the rational animal are the rational faculty, the appetitive faculty, the imaginative faculty, and the sense-perceptive faculty.
It is by the rational faculty that a human being embraces the sciences and the arts; distinguishes between noble and base actions and moral habits; deliberates about what ought to be done or not done; and, in addition, apprehends the useful and the harmful, the pleasurable and the painful. Of the rational, some is theoretical and some practical. Of the practical, some involves skill and some deliberation. By the theoretical, a human being embraces knowledge of what is not such as to be carried out at all; and by the practical, a human being becomes cognizant of what is such as to be carried out by means of his volition. By the skillful, the arts and crafts are embraced; and by the deliberative, there comes about thought and deliberation concerning each thing that ought to be carried out or not.
By the appetitive [faculty], there comes about the human appetite for seeking or fleeing something, longing for or loathing it, and preferring or avoiding it. By it, come about hatred and love, friendship and enmity, fear and trust, anger and contentedness, harshness and compassion, and the rest of the affections of the soul.
The imaginative [faculty] is what preserves the traces of sense-perceptions after they have been absent from sense and, in waking and sleep, combines some with others and separates some from others in combinations or separations, some of which are accurate and some false. In addition, among the actions and moral habits, it apprehends those that are useful and harmful, pleasurable and painful, but not those that are noble and base.
What pertains to the sense-perceptive [faculty] is evident. It is the one that apprehends sense-perceptible things by means of the five senses of which everyone is cognizant. It apprehends the pleasurable and the painful, but does not distinguish the harmful and the useful, nor the noble and the base.
5. Some nonrational animals are found to have the three remaining faculties apart from the rational one. For them, the imaginative faculty takes the place of the rational faculty in the rational animal. And some are found to have only the sense-perceptive faculty and the appetitive faculty.