Archive for the ‘Aristotle’ Category

Avicenna (Ibn Sina)

February 5, 2009


IBN SINA, Abu Ali al-Hussain Ibn Abdullah Ibn Sina, known in the West as Avicenna. He followed the encyclopedic conception of the sciences that had been traditional since the time of the Greek Sages in uniting philosophy with the study of nature and in seeing the perfection of man as lying in both knowledge and action. He was also as illustrious a physician as he was a philosopher.

His life is known to us from authoritative sources. An autobiography covers his first thirty years, and the rest are documented by his disciple al-Juzajani, who was also his secretary and his friend.

He was born in 370/980 in Afshana, his mother’s home, near Bukhara. His native language was Persian. His father, an official of the Samanid administration, had him very carefully educated at Bukhara. His father and his brother were influenced by Isma’ili propaganda; he was certainly acquainted with its tenets, but refused to adopt them. His intellectual independence was served by an extraordinary intelligence and memory, which allowed him to overtake his teachers at the age of fourteen.

It was he, we are told, who explained logic to his master al-Natili. He had no teacher in the natural sciences or in medicine; in fact, famous physicians were working under his direction when he was only sixteen. He did, however, find difficulty in understanding Aristotle’s Metaphysics, which he grasped only with the help of al-Farabi’s commentary. Having cured the amir of Khurasan of a severe illness, he was allowed to make use of the splendid library of the Samanid princes. At the age of eighteen he had mastered all the then known sciences. His subsequent progress was due only to his personal judgment.

His training through contact with life was at least equal to his development in intellectual speculation. At the age of twenty-one he wrote his first philosophical book. The following year, however, the death of his father forced him to enter the administration in order to earn his living. His judgment was swiftly appreciated. Having consulted him on medical matters, the princes had recourse to him also in matters of politics. He was a minister several times, his advice being always listened to; but he became an object of envy, sometimes persecuted by his enemies and sometimes coveted by princes opposing those to whom he wished to remain loyal. He took flight and was obliged to hide on several occasions, earning his living by medical consultations. He was imprisoned, escaped, lived for fourteen years in relative peace at the court of Isfahan and died at Hamadan, during an expedition of the prince ‘Ala’ al-Dawla, in 428/1037. He was buried there; and a monument was erected to him to celebrate the (hijri) millenary of his birth.

If his works are to be understood, they should not be thought of as those of a philosopher who lived in his books. He was occupied all day by affairs of state, and he laboured by night on his great works, which were written with astonishing rapidity. He was never safe, and was frequently compelled to move; he would write on horseback, and sometimes in prison, his only resource for reference being his memory. It has been found surprising that he differs from Aristotle in his works: but he quoted him without re-reading him, and, above all, his independence of mind inclined him to present his own personally worked out thought, rather than to repeat the works of another. Besides, his personal training was different. He was a man who lived in touch with the concrete, constantly faced with difficulties, and a great physician who dealt with specific cases. Aristotle’s Logic seemed to him insufficient, because it could not be applied in a way that was sufficiently close to life. Many recent controversies have been aroused since the study of his works has increased, especially at the time of his millenary, but the most plausible view of his personality is still the following: he is a scientific man, who attempts to bring the Greek theories to the level of that which needs to be expressed by the study of the concrete, when apprehended by a great mind.

The secret of his evolution, however, will remain concealed from us as long as we do not possess such important works as the Kitab al-Insaf, the ‘Book of Impartial Judgment’, which investigated 28,000 questions, and his ‘Eastern Philosophy’, of which we have only a fragment.

The corpus of Ibn Sina’s works that has come down to us is considerable, but incomplete. To the many questions that were put to him he replied hastily, without always taking care to keep his texts. Al-Juzajani has preserved several of these; others have been transmitted with different titles, others lost. The manuscript of the Insaf disappeared at the sack of Isfahan, in his own lifetime. The fundamental bibliography is that which al-Juzajani included in his biography, but it is not exhaustive. G. C. Anawati lists a total of 276 works, including texts noted as doubtful and some apocryphal works, in his bibliography of 1950. Mahdavi, in 1954, lists 131 authentic, and 110 doubtful works. Ibn Sina was known primarily as a philosopher and a physician, but he contributed also to the advancement of all the sciences that were accessible in his day: natural history, physics, chemistry, astronomy, mathematics, music. Economics and politics benefited from his experience as a statesman. Moral and religious questions (not necessarily pertaining to mysticism), Qur’anic exegesis, statements on ‘ufi doctrine and behaviour produced minor writings. He wrote poetry for instructional purposes, for he versified epitomes of logic and medicine, but he had also the abilitiesQof a true poet, clothing his philosophical doctrine in images, both in verse (as in his poem on the soul) and in prose, in symbolic narratives whose meaning has given rise to controversy [see Hayy b. yaqzan].

Medicine is the subject of separate works; but natural history and mathematics are thought of as parts of philosophy. Thus, his principal treatise on these sciences is included in the great Kitab al-Shifa’, ‘Book of Healing [of the Soul]’, in the same way as that on Metaphysics, while the famous Qanun fi ‘l-tibb, ‘Canon of Medicine’, is a separate work.

The Qanun appears to have formed a more consciously coherent whole than the philosophical works. Because it constituted a monumental unity, which maintained its authority until modern times when experimental science began, and because it still remained more accessible than Hippocrates and Galen, it served as a basis for seven centuries of medical teaching and practice. Even today it is still possible to derive useful information from it, for Dr. ‘Abd Allah Ahmadieh, a clinician of Tehran, has studied the therapeutics of Avicenna and is said to use them with good results, particularly in treating rheumatism.

The Qanun is the clear and ordered ‘Summa’ of all the medical knowledge of Ibn Sina’s time, augmented from his own observations. It is divided into five books. The first contains generalities concerning the human body, sickness, health and general treatment and therapeutics (French translation of the treatise on Anatomy by P. de Koning, 1905; adaptation giving an incomplete resume of the first book, in English, by Cameron Grüner, 1930). The second contains the Materia Medica and the Pharmacology of herbs; the page on experimentation in medicine (115, of the Rome 1593 edition) quoted in the Introduction to the French translation of the Isharat, 58, is to be found there. This passage sets out the three methods-agreement, difference and concomitant variations-that are usually regarded as characteristic of modern science. The third book deals with special pathology, studied by organs, or rather by systems (German translation of the treatise on diseases of the eyes, by Hirschberg and Lippert, 1902). The fourth book opens with the famous treatise on fevers; then follow the treatise on signs, symptoms, diagnostics and prognostics, minor surgery, tumours, wounds, fractures and bites, and that on poisons. The fifth book contains the pharmacopoeia.

Several treatises take up in isolation a number of the data in the Qanun and deal with particular points. Some are very well-known: their smaller size assured them of a wide circulation. Among the most widely diffused are treatises on the pulse, the medical pharmacopoeia, advice for the conservation of health and the study of diarrhoea; in addition, monographs on various remedies, chicory, oxymel, balsam, bleeding. The virtues of wine are not neglected.

Physicians were offered a mnemonic in the form of a poem which established the essentials of Avicenna’s theory and practice: principles, observations, advice on therapeutics and dietetics, simple surgical techniques. This is the famous Urjuza fi ‘l-tibb, which was translated into Latin several times from the 13th to the 17th century, under the title Cantica Avicennae (ed. with French trans. by H. Jahier and A. Noureddine, Paris 1956, Poeme de la Medecine, together with Armengaud de Blaise’s Latin translation).

Ibn Sina’s philosophical works have come down to us in a mutilated condition. The important Kitab al-Shifa’ is complete (critical text in process of publication, Cairo 1952-). Extracts chosen by the author himself as being the most characteristic make up the Kitab al-Najat, ‘The Book of Salvation [from Error]’, which is not an independent redaction, as was thought until 1937 (table of concordances established by A.-M. Goichon in La distinction de l’essence et de l’existence d’apres Ibn Sina, 499-503). The Kitab al-Isharat wa ‘l-tanbihat, ‘Book of directives and remarks’, is complete (trans. into Persian and French), as is the Danishnama-i ‘Ala’i, ‘The Book of Knowledge for ‘Ala’”, a resume of his doctrine written at the request of the prince ‘Ala’ al-Dawla. We have only fragments of the Kitab al-Insaf, ‘Book of Impartial Judgment between the Easterners and the Westerners’, which have been published by A. Badawi, and a small part of the Mantiq al-mashriqiyyin, ‘Logic of the Easterners’, which is the logic of his ‘Eastern Philosophy’, the rest of it being lost. A fairly large number of minor writings are preserved; they illuminate points of detail which are often important, but are far from completing the lacunas.

Ibn Sina’s was too penetrating a mind, and one too concerned with the absolute, not to venture outside the individual sciences. He looked for the principle and the guarantee of these, and this led him to set above them, on the one hand, the science of being, Metaphysics, and, on the other, the universal tool of truth, Logic, or ‘the instrumental science’, as the falasifa termed it.

As far as one can tell in the absence of several of his fundamental works, he seems to have been an innovator particularly in logic, correcting the excess of abstraction which does not permit Aristotle to take sufficient account of change, which is present everywhere and at all times in the terrestrial world; and, thus, of the difference between strict (mutlaq) meaning, and concrete meaning, specified by the particular ‘conditions’ in which a thing is actualized. As a physician, he enters into logic when he admits a sign as the middle term of a syllogism. He gives it the force of a proof, as the latter is recognized in a symptom in medical diagnosis (see Introduction to the French trans. of the Isharat).

In Metaphysics the doctrine of Ibn Sina is most individual, and is also illuminated by his personal antecedents. On the other hand, his thought was fashioned by three teachers, of whom, however, he knew only two by name: Aristotle and al-Farabi, who introduced several of

the great concepts subsequently developed by Ibn Sina. The third was Plotinus, who came down to him under the name of Aristotle, in the so-called ‘Theology of Aristotle’ [see aristutalis], which was composed of extracts from Plotinus’s Enneads, and presented as the culmination of Aristotle’s Metaphysics. This error of attribution dogs the whole of Avicenna’s work. As a born metaphysician he earned the title of ‘Philosopher of being’ but as a realist he wished to understand essences in their actualized state, so that he is just as much the ‘Philosopher of essence’. The whole of his metaphysics is ordered round the double problem of the origin of being and its transmission to essence, but to individually actualized essence (cf. Goichon, La distinction de l’essence et de l’existence d’apres Ibn Sina, Paris 1937).

It is at this point that a free interpretation of Aristotle and Plotinus gives him his theory of the creation of forms by emanation. This is linked with a cosmogony taken from the apocryphal Theology, but is also inspired by hylemorphism and Aristotelian data on the soul. The extensive place occupied in his thought by the intelligence prompts him to this startling view: the gift of being is linked with the light of the intelligence. Moreover, Ibn Sina is a believer; in accordance with Islam he believes in God as the Creator. None of the philosophies handed down from pagan antiquity takes account of this. He attempts to integrate dogma with his philosophical formulation. In fact, he does not succeed very well, but he continually works in this direction.

The first certitude apprehended by the human mind, he says, is that of being, which is apprehended by means of sense-perceptions. The idea of being, however, is so deep-rooted in man that it could be perceived outside of the sensible. This prefiguration of the Cartesian ‘Cogito ergo sum’ appears to have two causes: intuition (Hads) is so powerful in Ibn Sina (see in the Physics of the Danishnama the part that it played for him) that he bases himself here on a metaphysical apprehension of being; in addition, since the human soul, according to him, is a separate intelligence, which leads its own spiritual existence while being united with the body, it is capable of apprehending itself directly.

The second certitude is that the being thus apprehended in man, and in every existing thing, is not present there of necessity. The essence of ‘man’, ‘horse’ or ‘stone’ does not imply the necessity of the existence of a particular man or horse. Existence is given to actualized, concrete beings by a Being that differs from all of them: it is not one of the essences that have no existence in themselves, but its essence is its very being. The Creator is the First Cause; as a consequence of this theory the proof of the existence of God is restricted to Metaphysics, and not to Physics, as happens when God is proved to be the prime mover.

A Western controversy enters here: did Avicenna really believe in the analogy of being? It is true that he does not place the uncreated Being in the genus Substance or in a genus Being; but if he proceeds from knowledge of created beings to that of the uncreated Being, is not this a proof that he considers their natures to be allied? He certainly apprehends an analogy between the being of substance and that of accident, as he states explicitly, but did he go further? (see M. Cruz Hernandez, passim).

Ibn Sina did not formulate the distinction between the uncreated Being and created beings as clearly as did Thomas Aquinas, but the latter does base himself on Ibn Sina’s doctrine; only being is in God, God is in no genus and being is not a genus. He then sets out his thought precisely (cf. Vasteenkiste, Avicenna-Citaten bij S. Thomas, in Tijdschrift voor Philosophie, September 1953, citations nos. 12, 13, 14, 15, 20, 148, 330, pp. 460-1, 473 and 491).

With the principles established, two reasons for the omission of the conclusion are plausible, but neither involves the distinction not being made. Either, having set it out and admitted it, he withdrew it with difficulty because of the confusion between the data of Aristotle and Plotinus, or, as G. M. Wickens (Avicenna, scientist and philosopher, 52) suggests, he does not speak of it as a discovery because the celebrated distinction was then generally admitted-as Abu Hayyan al-TawHidi says. But Ibn Sina maintains that God, as he conceives Him, is ‘the first with respect to the being of the Universe, anterior to that being, and also, consequently, outside it’ (E. Gilson, L’esprit de la philosophie medievale2, 80-1).

However, this apparent impetus of Ibn Sina is interrupted by the data of Plotinus, for they inspire the emanatist theory of creation. The Qur’an, like the Old and New Testaments, explains creation by a freeQact of will on the part of God. For Ibn Sina, by way of Plotinus, the necessary Being is such in all its modes-and thus as creator-and being overflows from it. (Here the reader will ask himself the question: ‘Is it an analogous being? is it not rather the same being?’) Moreover, this emanation does not occur freely, and creation involves intermediaries, which are also creators. From the One can come only one. The necessary Being thus produces a single Intelligence. This, having a cause, necessarily possesses a duality of being and knowledge. It introduces multiplicity into the world; from it can derive another Intelligence, a celestial Soul and a celestial body. Ptolemy’s system becomes the framework of creative emanation; emanation descends from sphere to sphere as far as a tenth pure Intelligence, which governs, not a sphere, but our terrestrial world, which is made, unlike the others, of corruptible matter. This brings with it a multiplicity which surpasses human knowledge but is perfectly possessed and dominated by the active Intellect, the tenth Intelligence. Its role is demonstrated in a poetic and symbolic form in the ‘Tale of Hayy b. Yaqzan;, a name that refers to the active Intellect itself.

The philosophical origin of this active Intellect is the passage in the De Anima in which Aristotle refers by this name to the active part of the human soul. Ibn Sina irremediably mutilates the latter by taking away from it this active part, and with it its most noble action and its highest intellectual function: abstraction of intelligibles. This active Intellect, which, according to Aristotle, produces all intelligibles, is now a separate Intelligence. Thus the human soul receives them passively, and so cannot think except by leave of the Intellect; comprehension, knowledge and the sciences are now no longer its affair. It can elaborate only that which is given to it by the active Intellect. The latter produces not only these intelligibles but also all the substantial forms that are created in accordance with the models that it has conceived in conformity with the potentialities of matter. It is in this way, Ibn Sina replies to Plato’s anxious question (Parmenides, 131 a-b), that the concrete being can share in the Idea. The active Intellect has an ability which Plato sought for in vain: it apprehends the two series of relative perceptions, both the forms with their mutual relationships and the concrete beings with their mutual relationships; in addition, it apprehends their common repository, which is its own essence (cf. Goichon, La theorie des formes chez Avicenne, in Atti XII congr. intern. de filosofia, ix, at 137-8). A reply is also given to the question of Aristotle as to the provenance of form and the contribution of the Ideas to sensible beings (Metaph., Z 8 and M 5).

The human soul by itself can attain only the first three degrees of abstraction: sensation, imagination and the action of estimation that extracts individual non-sensible ideas. It then apprehends the intelligible that is given to it from outside. Intuition is due to its joining with the active Intellect.

Being and intelligence overflow like a river from the necessary Being and descend to the extreme limits of the created. There is an equally full re-ascent, produced by creatures’ love and desire for their creators, as far as the supreme Principle, which corresponds to the abundance of this gift. This beautiful concept, which could derive only from a soul inclined towards religion, has been thought of as mystical. The Risala fi ‘l-‘ishq, ‘The Epistle on Love’, however, is primarily a metaphysical explanation of the tendency of every being towards its good, and a physical explanation of the motion of the stars; they imitate in their fashion, which is material, the unceasing action of the pure Act. The spheres, in fact, thus imitate the unceasing desire of the celestial Souls which correspond to each one of them. The rational soul of man tends towards its good with a conscious motion of apprehension of, and love for, the active Intellect, and, through it, for the necessary Being, which is pure Good. In the highest states, however, it can tend directly towards the latter.

Ibn Sina believed firmly in the immortality of the soul. Corruption cannot touch it, for it is immaterial. The proof of this immateriality lies in its capability of apprehending the intelligibles, which are in no way material. He is much more hesitant on the question of the resurrection of the body, which he at first admits in the Shifa’ and the Najat, and then denies in the epistle A·Hawiyya, after indicating in the ‘Tale of Hayy b. Yaqzan’; that this dogma is often an object of temptations. He appears finally to have decided to understand it in a symbolic sense.

Among the fierce controversies to which Avicenna’s thought has given rise is the discussion as to whether or not he should be considered a mystic. At first sight, the whole range of expressions that he uses to speak of love’s re-ascending as far as to the Creator leads one to an affirmative interpretation-not in an esoteric way [see Hayy b. yaqzan], but in the positive sense of the love of God. The more one studies his philosophical doctrine, the more one finds that it illuminates these expressions. The stages of the Sufis, studied in the Isharat, leave rather the impression of experiences observed by a great, curious and respectful mind, which, however, does not participate. Ibn Sina is a believer, and this fact should be maintained in opposition to those who have made of him a lover of pleasure who narrowly escapes being a hypocrite, although there is so much seriousness in his life and such efforts to reconcile his philosophy with his faith-even if he is not always successful. He is far above the gnosis impregnated with occultism and paganism to which some would reduce him. Is he a mystic in the exact sense that the word has in Catholic theology? It reserves the word for one whose whole life is a great love of God, in a kind of intimacy of heart and thought with Him, so that God holds the first place in all things and everything is apprehended as related to Him.

Had it been thus with Ibn Sina, his writings would give a totally different impression. Nevertheless, at bottom he did perhaps apprehend God. It is in the simple expression of apprehension through the heart, in the secret of the heart (sirr), in flashes, however short and infrequent, that we are led to see in him a beginning of true mystic apprehension, in opposition to the gnosis and its symbols, for at this depth of the heart there is no longer any need for words.

One doubt, however, still enters in: his general doctrine of apprehension, and some of the terms that he uses, in fact, in texts on sirr, could be applied at least as well to a privileged connexion with the active Intellect, and not with God Himself (cf. Goichon, Le ‘sirr’ (l’intime du coeur) dans la doctrine avicennienne de la connaissance). Again, on this question, the absence of his last great work, the ‘Eastern Philosophy’, precludes a definite answer.

This irreparable lacuna in the transmission of his works does not allow us to understand in what respects he wished to complete, and even to correct, Aristotle, as he states in the prologue. As a hypothesis, suggested by his constant efforts to express the concrete and by his biography, we may suppose that he wished to make room for the oriental scientific tradition, which was more experimental than Greek science. The small alterations made to Aristotelian logic are slanted in this direction. In metaphysics, it is probable that he was shocked by the contradictions between Plotinus and Aristotle that were evident in the texts which the knowledge of the time attributed to one single author, and that he wished to resolve these anomalies by giving new explanations.

The transmission of Greek science by the Arabs, and the translation of the works of the Arabs into Latin, produced the first Renaissance in Southern Europe, which began in the 10th century in Sicily, flourished in the 12th round Toledo, and soon afterwards in France. The two principal works of Ibn Sina, the Shifa’ and the Qanun, made him an undisputed master in medicine, natural sciences and philosophy.

From the 12th to the 16th century the teaching and practice of medicine were based on him. The works of Abu Bakr MuHammad b. Zakariyya’ al-Razi were also known, and he was considered to be a better clinician; but the Qanun provided an irreplaceable didactic corpus, for the Kitab al-Kulliyyat fi ‘l-tibb of Ibn Rushd corresponded only with the first part of the Qanun. The latter was translated in its entirety between 1150 and 1187 by Gerard of Cremona, and, in all, eighty-seven translations of it were made, some of which were only partial. The majority were into Latin, but several Hebrew translations were also made, in Spain, Italy and the south of France. The medical translations are less good than those of the philosophical works; some words transcribed in Arabic from Greek were not understood or identified, and some Arabic technical terms were more or less transcribed in Latin, and remain incomprehensible. The Qanun formed the basis of teaching at all the universities. It appears in the oldest known syllabus of teaching given to the School of Medicine at Montpellier, a bull of Clement V, dating from 1309, and in all subsequent ones until 1557. Ten years later Galen was preferred to Ibn Sina, but the latter continued to be taught until the 17th century. The editing of the Arabic text, at Rome in 1593, demonstrates the esteem in which he was still held. (On the teaching of the works of Avicenna in the universities, see A. Germain, L’Ecole de medecine de Montpellier …, Montpellier 1880, 71; Stephen d’Irsay, Histoire des universites franaises et etrangeres des origines a nos jours, Paris 1933, i, 119; C. Elgood, A medical history of Persia … until the year 1932, Cambridge 1951, 205-9). Chaucer reminds us in the Prologue to the Canterbury Tales that no doctor should be ignorant of him. Almost all, in fact, possessed either fragments of the Qanun, especially the ‘Fevers’ and the ‘Diseases of the eyes’, or shorter writings, the treatise on the pulse or that on ‘Diseases of the heart’. All Arab authors, from the 7th/13th to the 10th/16th century, are dependent on Ibn Sina, even though they question him, like the father of Ibn Zuhr (Avenzoar), or augment and correct him, like Ibn al-Nafis, who recorded his discovery of pulmonary circulation in his commentary on the Qanun; he wrote a summary of the Qanun which any physician could obtain more easily than he could the original text.

In the West several physicians learned Arabic for the sake of the works of Ibn Sina. The first known influence appears in the works of a Dane, Henrik Harpestraeng, a royal physician who died in 1244. Arnold of Villeneuve, born at Valence, translated the treatise on the diseases of the heart, as well as some of the books of al-Kindi and other Arab authors. Some surgeons also quoted him as their authority: William of Saliceto in Italy, and his disciple Lanfranc, the founder of surgery in France; Guy of Chauliac, who died in 1368, and whose teaching employed Arabic terms and doctrines. At the University of Bologna, anatomy was still being taught in Arabic terms in the 14th century.

The Renaissance brought a violent reaction; Leonardo da Vinci rejected Ibn Sina’s anatomy, but, for want of another vocabulary, used the Arabic terms. Paracelsus burned the Qanun at Basle. Harvey dealt him a severe blow by publishing his discovery of the major circulation in 1628.

The natural sciences presented in the Shifa’ were much used by the mediaeval encyclopaedists, as were the treatises of al-Razi and apocryphal treatises. The ‘Treatise on Animals’ was translated by Michael Scot; Albertus Magnus employed the mineralogy (on Ibn Sina’s scientific influence, see G. Sarton, Introduction to the history of science, ii, passim.). In physics, Ibn Sina was an Aristotelian, and as such inferior to al-Razi, who had discovered the existence of the vacuum, which he himself denied. However, he opposed the theory of the transmutation of metals, and hence alchemy (for citations to this effect from several Arab authors, see the introduction by Holmyard and Mandeville to their translation of Avicennae De congelatione et conglutinatione lapidum, Paris 1927, 6-7).

Ibn Sina’s influence in philosophy was less absolute and more disputed, but more lasting, for the use made of him by St Thomas Aquinas embodied certain of his proofs in Catholic theology (cf. Goichon, La philosophie d’Avicenne et son influence en Europe medievale, Paris 1944, ch. III).

The translation of the Shifa’ came at a moment when Aristotle was scarcely known, and that only through the ‘Posterior Analytics’, the ‘Topics’ and the ‘Refutation of the Sophists’. The corpus that presented a ‘Metaphysics’, the ‘Treatise on the Soul’ and that on the ‘Heavens’, etc. seemed to hold another significance. It was, however, thought to be a simple commentary on Aristotle. For a century it received unreserved admiration; when Aristotle was better known, it was still thought that the Shifa’ augmented his work on the subject of the origin of the world, on God, the soul, the intelligence and angels. He was placed in the Neoplatonist and Augustinian traditions; his attempts to reconcile philosophy and faith corresponded with the ardent desires of the Schoolmen. He was forbidden by the decrees of 1210 and 1215, referring to ‘Aristoteles et sequaces ejus’, which banned Ibn Sina from the Sorbonne. But his role remained undiminished in private discussions.

After acclaim for his similarities with Christian thought came criticism of his divergences from it, violently initiated by William of Auvergne in 1230. Nevertheless, a pontifical decree of Gregory IX, in 1231, once more permitted the study of Ibn Sina’s philosophy. The lacunas, however, were now apparent. Nonetheless, the thought of all philosophers was nourished by his, to such a degree that it is impossible to tell what it would have been like without him. Latin scholasticism owes to his opponent, William of Auvergne, the fact that it received from him the distinction between essence and existence, which William considered that he had found in him.

Another current of thought, stemming from English centres of study, developed particularly in the Franciscan order. It saw Ibn Sina as more of a philosopher, augmenting Saint Augustine: the active Intellect was like the sun of minds and the internal Master. They believed that he opened up a whole mystic world. Roger Bacon and Duns Scotus were influenced by him. The latter, however, based his doctrine of the univocity of being on the same text that Thomas Aquinas had used to support the opposite doctrine.

Selection was gradually practised in the corpus of Ibn Sina. He took his definitive place, together with Saint Thomas Aquinas. The distinction between essence and existence became one of the fundamentals of Thomist philosophy. It gave an explanation for the immateriality of angels; Saint Thomas’s De Ente et Essentia is imbued with Avicennism. The better the theologian masters his own thought, the less he cites Ibn Sina (see the quotations in Vansteenkiste, op. cit.), but he still respects him. Saint Thomas’s commentators, Cajetan and Jean de Saint-Thomas, writing respectively at the end of the 15th century and during the 17th, still allotted to Ibn Sina the place that he had taken in Thomism, the place that is definitely his.

(A.-M. Goichon)

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