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known in the Latin West as Rhazes

(b. Rayy, Persia [now Iran], ca. 854; d. Rayy, 925 or 935)

medicine, alchemy, philosophy, religious criticism.

We possess very little authentic information about Rāzī’s life. He was born around 854 in Rayy, and directed a hospital in that town and later in Baghdad. Because of changes in the political situation and his personal standing at court, he returned on several occasions to Rayy. He died there in 925 or 935. Most of Rāzī’s philosophical and antireligious works are lost. Two treatises on ethics, Kitāb al-Tibb al-Ruhani (The Book of Spiritual Physick in Arberry’s translation) and Sirat al-Faylasūf (The Philosopher’s Way of Life), have been published. Several manuscripts exist of the work entitled Doubts Concerning Galen, which deals with philosophical as well as with medical questions. Abundant information about Rāzī’s philosophical teaching can be gleaned from the quotations and references to him made by his critics, many of whom belonged to the Ismā‘īlī sect and defended the strict hierarchical principle maintained by this sect against the equalitarian views propounded by Rāzī.

Rāzī rejected the notion that men can be stratified according to their innate capacities. All of them have, according to Rāzī, their share of reason, which enables them not only to deal with practical matters, but also to reach correct views on theoretical questions. With regard to some of these questions the judgment of simple unsophisticated people may be more valuable than that of the learned, who are befogged by erudite quibblings and subtleties.

Rāzī’s rejection of the hierarchical principle formed a part of his attack against religion. According to him, men, being naturally equal, did not need, in order to manage their affairs, the discipline imposed by religious leaders, who deceived them. The miracles supposed to have been worked by the prophets of the three monotheistic religions as well as by Mani were tricks. (The Tricks of the Prophets is the title of a lost treatise attributed to Rāzī.) Men of science like Euclid and Hippocrates were much more useful than the prophets. In fact, religion was definitely harmful, for fanaticism engendered hatred and religious wars.

Holding these views, Rāzī evidently could not subscribe to the doctrine, maintained by many Islamic authors, according to which the viable human societies were instituted by prophets. He may have followed a suggestion found in Plato in stating that society originated because of the need for a division of labor.

Rāzī’s refusal to accept the principle of absolute authority is in evidence not only in his antireligious polemics, but also in his attitude toward the traditional verities of science and philosophy and the eminent authors who had established these verities. Thus, in justifying his Doubts Concerning Galen, he observes: “Medicine is a philosophy, and this is not compatible with renouncement of criticism with regard to the leading [authors].” In this context he points to the example of disciples of Aristotle who criticized the latter and to that of Galen himself. This attitude is closely connected with Rāzī’s belief in the continuing progress of the sciences (which contrasts with the view of the Aristotelians that knowledge of the various sciences either has already reached its point of perfection or will necessarily reach it at some time in the future). According to Rāzī, a man of science, who knows the work of his predecessors, has because of this an advantage over them (however eminent they may have been) and can proceed to new discoveries. Rāzī’s distrust of established scientific dogmas is evident also in his readiness to give the benefit of doubt to reports concerning various phenomena that appeared to have no theoretical explanation. Thus he wrote a treatise (still unpublished) on properties, which contains a jumble of miscellaneous information concerning bizarre phenomena, some of them of magical nature. At the beginning of his introduction, Rāzī voices his conviction that he will be blamed for composing his treatise, the critics referred to being people who hasten to deny the statements they cannot prove. In fact, they are constantly observing phenomena similar to those the truth of which they deny. For instance—and this is but an example of many cited by Rāzī—they often see a magnet attracting iron. Yet, if someone claimed that there exists a stone attracting copper or glass, they would be quick to give him the lie. This open-minded attitude is somewhat reminiscent of that shown by Francis Bacon when discussing magic. Both of them appear to feel that all recorded facts, however strange and inexplicable, should be taken into consideration, because all may be of scientific interest.

This position may account for Rāzī’s interest in alchemy. In his writings on this science, he avoids the symbolism and occultism that are characteristic of Jābir ibn Hayyān, whom, as far as is known, he does not mention. The writings in question contain precise classification of various substances and precise accounts of the methods he follows in this science. Rāzī’s view of human reason determined to a considerable extent his physical doctrine; for his conceptions of space and time were based on the presupposition that the immediate a priori certainties (put down by the Aristotelians to the effects of the imaginative faculty and discounted in consequence) are a conclusive proof of truth. Thus the fact that everyone (all men having a share of reason) has (unless his judgment has been warped by the discussions of Schoolmen) an immediate certainty that a tridimensional space would exist even if all the bodies were to disappear, and that this space has no boundaries, demonstrates by itself the truth of these conceptions and suffices to refute the Aristotelian theories and arguments.

Basing himself in the main on these a priori certainties, Rāzī affirmed the existence contested by the Aristotelians of absolute space, which is pure extension, independent of the bodies that it contains; parts of it may be empty. This space extends beyond the limits of the world, is infinite. Rāzī also posited the existence of relative or partial space, equated with the extension of each body.

Rāzī had a similar approach to the problem of time. In attempting to disprove the thesis of the Aristotelians, who define as the number of the motion (of the highest sphere) and thus according to prior and posterior posit the dependence of its existence on that of the world, Rāzī, as in the case of space, appealed to the a priori certainties of untutored people, who, when called upon to imagine that the world has ceased to exist, have no doubt whatever that even in that case there would be a flow of time; for time is a substance that flows.

As in the case of space. Rāzī distinguished between two species of time, absolute time and limited time. The Aristotelian definition is, according to him, applicable to the latter, but not to the former, which is unmeasured and which existed before the creation of the world and will continue to exist after the latter’s dissolution. It is eternity (aiōn, dahr ). These conceptions are in some respects reminiscent of certain Zoroastrian conceptions of time (zurvān ). Analogies to them may also be found in Greek philosophy, in a passage attributed to Cicero (De natura deorum, 1.9.21), to the Epicurean Velleius, and, what may be even more to the point, given Rāzī’s view of himself as a disciple of Plato (see below), in a quotation purporting to give the opinion of the school of the Platonist Attikos (Proclus in Timaeum, Diehl, ed., III, 37; cf. L. Taran, “The Creation Myth in Plato’s Timaeus,” in J. P. Anton and G. L. Kustas, eds., Essays in Ancient Greek Philosophy [New York, 1971], 379, 397, n. 56).

Rāzī was an atomist, and his theory has a certain, although not very close, resemblance to that of Democritus; it differs profoundly from the teachings of Kalam. According to Rāzī, absolute matter, before the creation of the world, consisted of indivisible atoms having extension. For material, in contradistinction to geometrical, bodies are not divisible ad infinitum. On the other hand, if the visible material bodies were not composed of atoms, it would be necessary to suppose that the world was not created in time.

Having been mixed according to various proportions with particles of vacuum, the atoms produced the five elements, namely, earth, water, air, elemental fire, and the heavenly element. All the qualities of the elements, such as lightness and heaviness, opacity and transparence, and so forth, are determined by the quantity of matter, as compared with the particles of vacuum, which is found in them. The dense elements, namely earth and water, tend to move toward the center of the earth, while air and fire, in which the particles of vacuum are predominant, move upward. The heavenly element, in which there is an equilibrium between matter and the particles of vacuum, has circular motion.

In several passages, Rāzī states that he does not accept the philosophy of Aristotle, but that he is a disciple of Plato. The latter claim probably refers in the first place to some Hellenistic interpretation of the Timaeus. In Doubts Concerning Galen, Rāzī refers to two refutations made by the Greek physician of theories based on the doctrine of the Timaeus concerning the creation of physical bodies out of geometrical figures. In this connection Rāzī puts forward arguments for his personal brand of atomism. It may be noted that several of the physical conceptions of Rāzī are attributed in various Arabic philosophical and doxographical works to Plato. On the other hand, Rāzī’s equalitarianism is at the antipode of Plato’s political theory, which was adapted to a considerable extent by Arabic so-called Aristotelian philosophers.

As against the Aristotelians, Rāzī believed in the temporal creation of the world. In his cosmogony, which appears in his work Al-’ilm al-ilāhī (The Divine Science ), of which only fragments have been preserved, he appears to have adopted a gnostic myth. In this connection, it may he relevant to note that in the work that has just been mentioned he cites Mani’s writings. Rāzī himself is reported to have asserted that this view of the creation of the world was held by Socrates. (See Nāsir-i Khusraw, Kitāb Jāmai‘al-Hikmatayn, H. Corbin, ed. [Teheran, 1953], 211–213. This account agrees in all the main points with the one found in another work of Nāşir-i-Khusraw entitled Kitāb Zād al-Musāfirin. The second account may be found in P. Kraus’s edition of Razs Opera philosophica, 282, and in S. Pines, Beiträge zur Islanu’schert Atomenlehre, 59.) According to this cosmogony, there exist five preeternal principles: creator, soul, matter, time, and space; for the doctrine of temporal creation can be maintained only if it is supposed that several preeternal principles exist. The existence of one such principle only—which would be immutable—entails the eternity of the world.

The soul, which had life but no knowledge, conceived the desire to be conjoined with matter and to produce in the latter forms that procure pleasures of the body. Matter, however, was refractory. Thereupon, the creator in his mercy created this world, which contained forms in which the soul could take pleasure, and through the intermediary of which it could engender men. But the creator also sent the intellect, which is part of his substance, in order to waken the soul; for the latter is asleep in its temple, which is man. It is the task of the intellect to teach the soul that this created world is not its veritable home and that he cannot achieve in it happiness and tranquillity. Man can be freed from bondage to matter only through the study of philosophy. When all human soul will have achieved liberation, the world will be dissolved, and matter, being no longer provided with forms, will revert to its primeval state— that is, that of dispersed atoms.

A very similar cosmogony is attributed by the thirteenth-century author al-Kātibī to members of the Hellenistic pagan community of the town of Harran. Rāzī’s cosmogony translated into German by H.H. Sehaeder (see bibliography) was quoted and half-seriously adopted by Thomas Mann in Josef unci Seine Brihier. Mann docs not name his source, but refers to an exposé (Referat ) which he used.

The cosmogony in which the conjunction of the soul with the matter is considered as the origin of suffering and Rāzī’s pessimistic view (indicated in another fragment of the Divine Science [quoted by Maimonides]) that in our world evil is predominate over good, seem to call for an ascetic ethical doctrine. The two ethical treatises of Rāzī that are extant, however, are moderate in this respect. The Book of Spiritual Physick sets forth Plato’s doctrine concerning the three souls of man: the rational, the spirited, and the concupiscent. Only the first is regarded as surviving the death of the body. It is for the sake of the rational soul that the two others are generated. All three souls should avoid both excess and deficiency in their activities and functions. In the case of the rational soul deficiency means failure to attempt to investigate both the things of this world and in particular the body in which the soul is lodged, and the destiny of the soul after death. Excess means such total preoccupation with this enquiry that the needs of the concupiscent soul are not met.

In his other ethical treatise, The Philosopher’s Way of Life, Rāzī mentions that people point out that Socrates’ way of life was incompatible with the workings of orderly society. According to Rāzī, this cynical tradition concerning Socrates is correct only as regards the beginning of his career (as a philosopher). Afterward, he took part in social activities and did not lead an excessively ascetic life. Like The Book of Spiritual Physick, this treatise, too, strikes the note of moderation. Rāzī’s attitude toward animals is part of his ethics. Only carnivores and noxious animals such as snakes may be killed. The killing of the others is lawful for only one reason. Souls lodged in the bodies of animals cannot be liberated; only souls subsisting in human bodies achieve liberation. Hence, given the doctrine of transmigration, according to which a soul may pass from an animal to a human body, the killing of an animal may set it on the path of liberation.

Rāzī’s medical works, some of which were translated in the Middle Ages into Latin, include monographs, such as a treatise on smallpox and measles, and comprehensive manuals, such as AlHai (Continens of the Latin ), a voluminous work containing extracts from Greek and Arabic physicians concerning the various medical problems and accounts of Rāzī’s personal experiences and conclusions.

Rāzī’s clinical observations have been edited by M. Meyerhof (see bibliography). His critical attitude toward the traditional, that is, Galenic, medical theories and observations comes out very clearly in his Doubts Concerning Galen. Thus, he observes, speaking of Galen’s descriptions of fevers, that in the hospitals of Baghdad and of Rayy he noted throughout many-years both the names of those whose illness followed the course laid down in “those books” and of those whose illness did not conform to these descriptions, and found that the latter were as numerous as the former.

Rāzī also indicated that on some points his medical experience was much more abundant than that of Galen. Thus he observed—in connection with a remark by Galen that he had noted only two cases of a certain urinary disease—that the disease may have been rare in Galen’s country. Rāzī himself encountered in Iraq and al-jebel more than a hundred cases of the disease.

One of the very numerous medical points on which Rāzī took issue with Galen was the rule formulated by Galen that a thing that has the property of cooling or warming is always colder or warmer than things cooled or warmed by it. According to Rāzī, this a priori rule is not valid in medicine. Experience shows that in cases of illness a beverage that is only moderately warm can heat to a degree that is much greater than its own heat. In such cases the beverage triggers in the human body a passage from potentiality into actuality.

In his critique of Galen’s theory of vision. Rāzī indicates that some of the errors of his predecessor were caused by the latter’s excessive recourse to mathematics. His own theory, which by and large is reminiscent of Aristotle’s doctrine, has one peculiarity: Rāzī considered that the air carrying the visual images passes through the hollow optic nerve and reaches the ventricles of the brain that contain the animal spirit. A major point on which Rāzī disagreed with Galen has both medical and philosophical aspects. It concerns the nature of the soul, which Rāzī regarded as a substance, whereas Galen considered it as a mixture. Rāzī appeared to think that the brain is an instrument of the soul.

Rāzī’s antireligious attitude and his interest in alchemy provoked attacks in which even his medical competence was questioned. Btruni, who compiled a list of Rāzī’s works, cites a dictum in which Rāzī was accused of destroying the wealth of people (by means of alchemy), destroying their bodies (by means of medicine), and corrupting their souls (by means of his defamation of the prophets). Biruni had a great admiration for Rāzī as a physician (and may have, moreover, been influenced by his refusal to accept without question the authority of Aristotle), but he did not defend him. or not wholeheartedly, on the two other counts. To some extent this attitude was characteristic. But Biruni’s criticism was mild compared with that of many other authors. In medicine Rāzī had a great name: but in other areas, philosophy for example, his reputation was dubious.

There is a certain affinity between his attitude (notably his acceptance of what he regarded as a priori certainties) and that of the unorthodox philosopher Abu’l-Barakāt. and their conceptions of space are similar. On the other hand some of the leading so-called Aristotelian philosophers manifested their disdain for him.

Ibn Sīnā suggested that he should have confined himself to dealing with boils, urine, and excrement and should not have dabbled in matters beyond the range of his capacity. In doing so he exposed himself to contempt. Maimonides asserted that he was only a physician, that is, not a philosopher. It may be noted that Ibn Sina and Maimonides were themselves physicians. But they were also to some extent Aristotelians, and hence intolerant of Rāzī’s reliance on immediate certainties—and perhaps also of his readiness to accept empirical evidence that was apt to upset established doctrines.


See P. Kraus, ed., Bīrunī, Risāla fi Fihrist Kutub Muḥammad ibn Zakariyā al-Rāzi (Paris, 1936); J. Ruska, “Al-Birunī als Quelle fur das Leben und die Schriften al-Rāzī’s in lsis, 5 (1922), 26 50; Al Ḥāwī the most voluminous of Rāzī’s medical works (Hyderabad, 1955–1968); M. Meyerhof, “Thirty-Three Clinical Observations by Rhazes” in Isis, 23 (1933), 322 ff;A Treatise on the Smallpox and Measles, W. A. Greenhill, trans. (London, 1847); P. de Koning, Traite sur le Calcul les Reins el la Vessie (Leiden, 1896); J. Ruska, “al-Rāzī als Chcmiker,” in Zeitschrift fur angewandte Chemie (1922), 719 ff; “Die Alchemic al-Rāzī’s” in Der Islam, 22, 719 ff; and “Oberseizung und Bearbeitungen von al-Rāzī’s Buch Geheimnis der Gcheimnisse,” in Quellen und Studien zttr GeschUhte der Naturwissenschaften und der Medizin, 4 (1935). Kitab al-Asrdr wa-sirr at-Asra (Teheran, 1964). P. Kraus,Abi Bakr Mohammadi Zachariae Ragemsis (Rāzīs) Opera philosophical Fragmenta que quae supersunt, Pars Prior (Cairo, 1939), contains the Arabic text of Rāzī’s two ethical treatises and practically all the known philosophical fragments. Persian quotations arc given both in Persian and in Arabic trans.

See also P. Kraus, “Raziana,” in Orientalia n.s. 4 (1935), 300 ff; 5 (1936), 35 ff; H. H. Schaedcr, in Zeit-sehrift der Deutschcn Morgenldndischen Gesellschaft59 , 228 ff; S. Pines, Beitrage zur Islamischen Atomenlehre (Berlin, 1936); “Rāzī Critique de Galien,” in Actes du 7e Congres international dliistoire des sciences (Jerusalem, 1955), 480–487; and “What Was Original in Arabic Science,” in Scientific Change, Symposium on the History of Science (Oxford, 1961), 181 ff- M. Mohaghegh, Filsuf-Rayy MuhammadIbn-i-Zakariyai-Rāzī (Teheran, 1970), in Persian, a comprehensive work on Rāzī as a philosopher.

A detailed bibliography, to 1924, is found in G. Sarton, Introduction to the History of Science, I, 609–610.

Shlomo Pines

al-Rāzī, Abū Bakr Muḥammad ibn Zakariyyā

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al-Rāzī, Abū Bakr Muḥammad ibn Zakariyyā (850–925 (AH 236–313)). Muslim philosopher, physician, and pre-eminent medical writer; in Europe he became known as Rhazes (Rasis in Chaucer). He wrote a large number of books, including Kitāb al-Mansūrī (tr. into Lat. as Liber Almansoris), Kitāb al-Mulūkī (Liber Regius) and a vast encyclopaedia, completed after his death by his pupils, Hāwī (Continens, first tr. in 1279 and later one of the first books to be printed, five times between 1488 and 1542). He ended his days blind, and refused treatment, saying that he had been in the world so long that he had seen enough of it.

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Abu Bakr Muhammad Ibn Zakariyya Al-Razi

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