The Arabians received Aristotle's works from the Syrians and Persians,
who in 529 gave shelter to the philosophers banished from Athens by
Justinian. The most important of the translators and commentators who
made Aristotle and Plato intelligible to these Oriental peoples are
David the Armenian (sixth century), the Nestorian Christians of
the schools of Edessa and Chalcis (fifth and sixth centuries), and
Honain ben Isaac, who, in the ninth century, began a series of
translations from Syriac into Arabic. It is, therefore, beyond dispute
that the Arabians owe their knowledge of Greek philosophy to the Syrian
Sources. The classic works on Arabian philosophy are: Munk,
Mťlanges, etc. (Paris, 1859); articles by Munk in the
Dictionnaire des sciences philosophiques; Renan's De
Philosophia peripatetica apud Syros (Paris, 1852), and his
AverroŤs et l'AverroÔsme (Paris, 1869). To the
bibliography given by Weber (p. 211) and Ueberweg (p. 406) add M.
Forget's articles in Nťo-Scolastique (1894), Figuier,
Vies des savants du Moyen Age (Paris, 2883), and De Vaux,
Avicenne (Paris, 1900).
SKETCH OF SYSTEMS OF PHILOSOPHY AMONG THE ARABIANS
Speculative thought among the Arabians passed through the following
1. Primitive unquestioning belief in the Koran. From the middle
of the seventh century until the middle of the eighth, the authority of
the Koran was supreme among the followers of Mahomet.
2. Motazilites, or dissidents. This sect represented a
rationalistic movement against the orthodox fatalism and
anthropomorphism, -- a movement occasioned by the contact (A.D. 750)
of the Mussulman with the civilization of Persia, Babylonia, and
3. MotacallimÓn, or professors of the word. These were the
first theologians of Islam. In their effort to expound the Koran
rationalistically, and yet without exceeding the limits of orthodox
belief, and in the use which they made of the philosophy of the Greeks,
they resemble the schoolmen of Christian Europe. The Motacallimin
received encouragement and patronage from the Abbassides, who began to
rule as caliphs about the year 750.
4. Sufis, or mystics. These represented a more extreme phase of
the theological reaction against rationalism. They flourished chiefly
in the Persian portion of the Arabian empire. Distrusting reason and
philosophy, they taught that the only source of truth is the Koran, and
that the reading of the Koran is to be supplemented by ecstatic
5. Philosophers. The philosophical movement among the Arabians
extended from the ninth century to the end of the twelfth. The
philosophers were, in a sense, the continuators of the dissident
movement. As a rule, they disregarded the authority of the Koran, and
built their systems of philosophy upon lines traced by the Greeks,
whose works they obtained from the Syrian Christians. They were opposed
by the mystics and persecuted by the caliphs both in Asia and in
The chief philosophers are: (1) Among the Arabians of the East,
Alkendi (died 870), Alfarabi (died 950), Avicenna
(Ibn Sina) (980-1037), and Algazel (1059-1111); (2) Among the
Arabians of the West, that is, in Spain, Avempace (died 1138),
Abubacer (1100-1185), and Averroes (Ibn Roshd) (1126-1198).
Avicenna, physician, philosopher, and theologian, was born in
the province of Bokhara. He composed a medical Canon and numerous
philosophical works in which he expounded the doctrines of Aristotle
and of his Greek commentators. He devoted special attention to
metaphysics, maintaining the existence of a Sovereign Intelligence as
the highest reality, and of matter, or the non-existent, as the lowest
in the scale of being. The first emanation from the Supreme
Intelligence is the active intellect, to which Avicenna assigns a
metaphysical as well as a psychological role, teaching that it is
the source of all heavenly and earthly intellects, and that it is the
principle by which the potentially intelligible becomes actually
intelligible to the human mind. 
 St. Thomas, Contra Gentiles, II, 42; Opusculum De
Substantiis Separatis, Cap. 10. cf.Archiv f. Gesch. der
Phil., X, 2 (January, 1904).
Despite these Neo-Platonic principles, Avicenna maintained the
Aristotelian doctrine of sensation and the moderate realistic doctrine
of universals. The latter he expressed in the formula so often quoted
by Albert and other schoolmen: "Intellectus in formis agit
universalitatem." His definition of the soul  is identical with
Aristotle's: "Completa definitio animae est perfectio prima vel actus
primus corporis organici." Still, he returns to Neo-Platonic principles
in his account of the origin of intellectual knowledge, as when  he
teaches that intelligible species are acquired in two ways: by
rational discourse, or demonstration, and by infusion ("infusio vel
 De Anima, II, fol. 5. This and following quotations from the
works of the Arabians are given by StŲckl, Gesch. der Phil. des
Mittelalters, II, 25ff.
 Op. cit., VIII, fol. 23.
Both St. Thomas and Albertus Magnus ascribe to Avicenna the doctrine of
the unity and transcendency of the active intellect. The former
says:  "Intellectum agentem ponit Avicenna quandam substantiam
separatam,"  "Avicenna ponit quod intellectus agens est unus in
omnibus, quamvis non intellectus possibilis."
 C. G., II, 74.
 Op. cit.. II, 76.
Historical Position. Avicenna was the first of the Arabians of
the East to depart from the Neo-Platonic interpretation of Aristotle.
The remnant of Neo-Platonism in his system of philosophy is proof of
his inability to escape altogether from the influence of his
predecessors. AverroŽs, who represents the Arabian philosophy of
the West, looked upon Avicenna as a materialistic pantheist; Algazel
and other mystics regarded him as a rationalist; and many of the
schoolmen spoke of him as the first of the mediaeval Occasionalists.
AverroŽs was born in the year 1126 at Cordova. His career,
like that of Avicenna, shows the bitterness of the intolerance
prevailing among the followers of Islam, inclined as they were to side
with the mystics, whom they regarded as orthodox, rather than with the
philosophers, whom they suspected of hostility to the Koran. Like
Avicenna, too, he was a physician. Exiled to Morocco on account, it is
said, of his political doctrines, he died there in the year 1198.
AverroŽs was regarded as the greatest of all the Arabian commentators
of Aristotle. He composed besides his commentaries several treatises on
astronomy, medicine, and philosophy, and also a controversial work,
Destructio Destructionis, in answer to Algazel's Destructio
Philosophorum. His admiration for Aristotle knew no bounds.
"Aristotelis doctrina," he says, "est summa veritas, quoniam ejus
intellectus fuit finis humani intellectus." 
 Prooemium in Aristotelis Physica.
In logic AverroŽs limits himself to the task of commenting
on Aristotle's Organon. He adopts Avicenna's formula,
"Intellectus in formis agit universalitatem." Science, he teaches,
treats of individual things under the form of universality which the
intellect abstracts. 
 Compendium Metaphysica, Tract. II.
Metaphysics. Matter and form are the principles of being. Matter
is not to be conceived as identical with not-being. It is the eternal
potency out of which the First Mover extracted (extractio is to
be substituted for creatio) the successive forms, or forces,
which determine matter to different modes of existence. 
 Cf.Destructio Destructionis, Disp. 1.
Heavenly bodies are endowed with a more excellent kind of form than are
terrestrial bodies. The Prime Mover imparts motion to the celestial
sphere, which in turn moves the planetary spheres. The mover of the
sphere of the moon is the active intellect. 
 "Intellectus autem agens ordinatur ex ultimo horum in ordine et
ponamus ipsum esse motorem orbis Lunae." Compend. Metaph.,
Psychology. The most characteristic of AverroŽs'
psychological doctrines is that of the unity of the active intellect.
Whenever Aristotle speaks of the intellect as separate from matter or
unmixed with matter, AverroŽs understands him to mean that the
power by which the potentially intelligible is rendered actually
intelligible is physically and topically separate from the body and is
numerically one and common to all men. The passive intellect, which
AverroŽs calls the material intellect, is also one: "Possumus
opinari intellectum materialem esse unicum in cunctis individuis." 
In the context of the passage just quoted, the active and passive
intellects are called parts of the same intellect. Still, in a certain
sense, it is true that there are as many intellects as there are
individuals, for the separate intellect is communicated to the
individual soul, just as the light, while remaining one, is
communicated to the multiplicity of objects which it illuminates. 
This communication is described as continuatio or copulatio, and the
schoolmen understood AverroŽs to mean that the continuation of the
individual soul with the transcendent intellect takes place by means of
the phantasmata of the sensitive soul. 
 De An., fol. 165.
 Destr. Destr., Disp. 1, dubium 8.
 Cf. St. Thomas, C.
G., II, 73; III, 43; also, Opusculum De Unitate Intellectus
contra Averroistas. Cf. Albert, De Natura et Origine
Anima and De Unitate Intellectus contra Averroem.
It is evident from this doctrine that, according to AverroŽs, the
individual soul contains nothing superior to matter, and is, therefore,
corruptible. The impersonal intellect is immortal; but there is no personal
immortality. Nevertheless, AverroŽs apparently believed in
personal immortality. St. Thomas represents him as saying: "Per
rationem concludo de necessitate quod intellectus est unus numero,
firmiter tamen teneo oppositum per fidem."  The distinction to which
allusion is made in this quotation was adopted by the Averroists of the
fourteenth and fifteenth centuries, when they maintained, in opposition
to the fundamental principles of Scholasticism, that what is true in
philosophy may be false in theology, and vice versa.
 Opusc. XXII, p. 493.
Historical Position. AverroŽs was known as the commentator
of Aristotle. He intended, no doubt, to reproduce as faithfully as he
could the doctrines of the Stagirite. He did not, however, succeed in
breaking with the pantheistic and rationalistic tradition of the
Moorish schools; indeed, he emphasized in his commentaries those points
of Aristotle's teaching which were opposed to Christian dogma, so that
St. Thomas was obliged to judge him "non tam Peripateticus quam
Peripateticae philosophiae depravator."