AVICENNA (Abū 'Alī al-Ḥusajīn ibn 'Abd Allāh ibn Sīnā, called Avicenna by Latin Scholasticism):—One of the greatest Arab philosophers, a celebrated physician, encyclopedic in his knowledge and therefore called the “chief sage” and “the third master,” after Aristotle and al-Fārābī. Born in 980 in a village in the region of Bochara, in the eastern part of Persia, he spent his life there; for a time he was wazīr, that is, minister, to the prince Sams ad-Dawlah in Hamadān; he endured several months of imprisonment for political reasons; but he devoted the greater and better part of his life to the study of philosophy, medicine, and the sciences. He died in Hamadān in 1037.
A. created a great philosophical system of a character
A. wrote about a hundred works, most of them brief, though some were of considerable size, such as the philosophical encyclopedia al-Šifā’, that is, The Healing, and the Canon of medicine. Most of these works are in Arabic, and some in Persian, A.’s mother tongue. The Healing consists of four principal sections: logic, physics, the mathematical disciplines, and metaphysics, and is the most detailed exposition of his system. The section devoted to physics consists of eight parts, the sixth of which deals with the soul: it is the Liber sextus naturalium, well known to Latin scholasticism, which was also acquainted with his metaphysics. The Kitāb an-nağāt is a concise extract from The Healing. This book was published, together with the Canon, in Rome in 1593. Logic and metaphysics are also expounded in the Kitāb al-šifārāt wat-tanbīhāt. Among the shorter philosophical works are an epistle on the division of the sciences and various treatises on psychology. His various writings on mystical subjects should also be mentioned. He also wrote on alchemy, music, and astronomy, and in his letters dealt with various questions of science and philosophy.
In logic, which according to him also embraces rhetoric and poetics, A. follows Aristotle and Porphyry’s Introduction. Syllogistic, however, is treated only briefly.
Wisdom (al-ḥikmah), which comprises all the sciences, is divided into theoretical and practical. The former, which tends toward truth, comprises physics, mathematics, and theology; the latter, which is directed toward the good, consists of ethics, economics, and politics. The subject of physics is bodies composed of matter and form, endowed with primary and secondary qualities or powers, in a state of rest or motion. Bodies are in place and in time, the concept of the latter deriving from that of motion. Every body has its own natural place. A. demonstrates that the void does not exist. He also deals with the problem of the infinite, which he admits with respect to the past; moreover, bodies are potentially divisible to infinity, as is motion.
Although in his doctrine of the soul A. also shows himself a faithful disciple of Aristotle, in certain respects he nevertheless departs from his teacher. By various arguments he demonstrates the existence of the soul, its spirituality, and hence its immortality: it is a simple substance that expands throughout the body as the trunk expands its branches, and this substance is what man truly is. Soul and body, wholly different from one another, are dependent on each other not substantially, but «per accidens», and therefore the soul does not perish with the death of the body. It does not, however, exist before the body, but is created at the very moment of the generation of the body to which it is destined and for which it consequently receives a special preparation. When it leaves the body, each soul remains an entity distinct from the other souls. As a consequence of this individuality, A. rejects metempsychosis. The soul may be of three kinds: vegetative, animal, and rational, of which the first is characteristic of plants, the second of animals, and the third of man. In treating of the latter two, A. observes that it is within the animal’s power to grasp particulars and to move voluntarily, whereas the rational soul grasps universals and acts through free choice. The animal soul performs an incomplete work of abstraction on the data furnished by the senses, without wholly stripping them of their matter. It has four faculties: the formative, the cogitative, opinion (al-tushm), and memory, which together constitute internal perception, to be distinguished from external perception, constituted by the activity of the senses.
The rational soul, or intellect, is first divided into theoretical and practical. The theoretical is the perceptive faculty and stands in relation to the principles superior to it, which it obeys. Within the perceptive faculty one must distinguish the material intellect, which is the absolute possibility of knowing; the possible intellect, which is actual with respect to the former and has acquired the first and necessary truths; and the intellect in act, which is in a state of perfect preparation for the acquired intellect, when the apprehension of forms takes place. Furthermore, some men possess the holy spirit, which would constitute a fifth stage, in which things are known immediately. Now the intellect in potency becomes actual only through the operation of the intellect that is always in act; this, however, is a substance outside man, in which the intelligible forms of the objects of knowledge reside. In order to know a thing, the rational soul must therefore be united with the agent intellect, without actually becoming that intellect. The soul grasps universals or intelligibles, initially abstracted from the particulars conveyed to it by the senses, apprehending them in act through its union with the agent intellect, in which these intelligibles reside. Particulars, besides being perceived by the senses, are also understood by the intellect, not, however, insofar as they are particulars, but insofar as they are effects of their cause: this understanding constitutes knowledge of particulars, which must be distinguished from their perception by the senses. The soul thus rises from sense and reaches the agent intellect: it therefore has one side turned downward and another turned upward; it withdraws from the senses in order to draw ever closer to universal realities and thus return to its origin and essence.
Metaphysics, or first philosophy, or al-illāhijāt, is the science of abstract concepts concerning all beings and the first principles of the sciences and of the world of supraterrestrial beings, as well as God. In the hierarchy of beings, the supreme place is occupied by the necessary being, God, whose existence A. seeks to demonstrate: a being that has neither body nor matter nor form, that is not divisible, and in…
in which there is therefore no part earlier or later, but everything that is possible in him is necessary at the same time. God is truth, goodness, power, life, and pure knowledge, but despite all this he is a single cause; he is the One and the Only. He knows particulars in a universal manner. His essence has neither genus nor difference and cannot be defined. It is impossible to imagine him as nonexistent. From this being there emanates the world of ideas, of pure intelligences, then the world of essences, clothed in a certain manner with matter, which govern the bodies of the spheres and through them the elements; thereafter the physical world with the forces infused into bodies, and finally the world of bodies. A. ingeniously, though unpersuasively, sought to deduce the multiplicity of the sublunary world from the One of the necessary being, through the knowledge that the first caused being has of itself as first, as possible in itself, and as necessary from the first; and likewise of the lower emanations, arriving at the agent intellect, which governs the world of man. A. also attributes soul and body to the spheres and compares their soul with the animal soul of man. The spherical soul seeks to resemble the supreme good and thus to enter a state of perfection. The first cause of the motion of the spheres is the first mover, God, who nevertheless stands above all motion. Avicennian emanationism is already found among the Arab philosophers in al-Fārābī. A. also dealt with the problem of evil. He asserts that, in the judgment of God, evil is only accidental; it is merely negative, a lack or defect, and does not affect intelligibles, but strikes only particulars or individuals. Good in the world is numerically and quantitatively superior to evil. A. is therefore an optimist.
One enters the field of mysticism with the doctrine concerning the fate of rational souls after their separation from bodies. They then tend toward perfection, which is their essence, seeking to become increasingly intelligent and wise and to assimilate themselves ever more closely to God. To prepare for this life, man must already in this world lead an intellectual existence superior to the senses. Thus the soul may attain a state of happiness. When, on the other hand, it is impure, it suffers, and its sufferings diminish as it becomes increasingly purified. After the death of the body, spiritual souls enter into the mercy of God, while the utterly wicked souls suffer terrible punishments.
In addition to his philosophy, A. owes the great fame he enjoyed to the medical art, in which he was one of the great masters, followed in certain doctrines even during the last century. His Canone della Medicina represents a grandiose attempt to arrange in a system all the medical doctrines of Hippocrates and Galen, together with the biological conceptions of Aristotle. Avicennian doctrine is based on the humoral theory of Hippocrates. All physicians have admired in A., besides his clear and suggestive style, the precision of his therapeutic indications and the clarity of his clinical histories.