Abū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā (Persian/Arabic: ابو علی الحسین ابن عبدالله ابن سینا); (born c. 980 near Bukhara, Khorasan, died 1037 in Hamedan), also known as Ibn Seena and commonly known in English by his Latinized name Avicenna (Greek Aβιτζιανός), was a Persian polymath and the foremost physician and philosopher of his time. He was also an astronomer, chemist, geologist, Hafiz, logician, paleontologist, mathematician, physicist, poet, psychologist, scientist, Sheikh, soldier, statesman, teacher and Islamic theologian.
Ibn Sīnā wrote almost 450 treatises on a wide range of subjects, of which around 240 have survived. In particular, 150 of his surviving treatises concentrate on philosophy and 40 of them concentrate on medicine. His most famous works are The Book of Healing, a vast philosophical and scientific encyclopaedia, and The Canon of Medicine, which is a standard medical text at many Islamic and European universities. The Canon of Medicine was used as a text-book in the universities of Montpellier and Louvain as late as 1650. Ibn Sīnā developed a medical system that combined his own personal experience with that of Islamic medicine, the medical system of the Greek physician Galen, Aristotelian metaphysics (Avicenna was one of the main interpreters of Aristotle), and ancient Persian, Mesopotamian and Indian medicine. He was also the founder of Avicennian logic and the philosophical school of Avicennism, which were influential among both Muslim and Scholastic thinkers.
Ibn Sīnā is regarded as a father of early modern medicine, and clinical pharmacology particularly for his introduction of systematic experimentation and quantification into the study of physiology, his discovery of the contagious nature of infectious diseases, the introduction of quarantine to limit the spread of contagious diseases, the introduction of experimental medicine, evidence-based medicine, clinical trials, randomized controlled trials, efficacy tests, clinical pharmacology, neuropsychiatry, risk factor analysis, and the idea of a syndrome, and the importance of dietetics and the influence of climate and environment on health. He is also considered the father of the fundamental concept of momentum in physics, and regarded as a pioneer of aromatherapy for his invention of steam distillation and extraction of essential oils. He also developed the concept of uniformitarianism and law of superposition in geology.
"One of the most famous exponents of Muslim universalism and an eminent figure in Islamic learning was Ibn Sina, known in the West as Avicenna (981-1037). For a thousand years he has retained his original renown as one of the greatest thinkers and medical scholars in history. His most important medical works are the Qanun (Canon) and a treatise on Cardiac drugs. The 'Qanun fi-l-Tibb' is an immense encyclopedia of medicine. It contains some of the most illuminating thoughts pertaining to distinction of mediastinitis from pleurisy; contagious nature of phthisis; distribution of diseases by water and soil; careful description of skin troubles; of sexual diseases and perversions; of nervous ailments."
Avicenna created an extensive corpus of works during what is commonly known as Islam's Golden Age (ca 10-11 century CE), in which the translations of Graeco-Roman, Neo- and Mid-Platonic, and Aristotelian texts by the Kindi schools were commented, redacted and developed substantially by Islamic intellectuals, as well as building upon Persian and Indian mathematical systems, astronomy, algebra, trigonometry, and medicine. Samanid dynasty in Greater Khorasan and central Asia as well as Buwayhid on in western part of Persia and Iraq could provide a thriving atmosphere for scholarly and cultural development. Under the Samanids, Bukhara rivalled Baghdad as a cultural capital of Islam.
The study of Quran and Hadith throve in such a scholarly atmosphere. Philosophy Fiqh and theology kalam were further developed, most noticeably by Avicenna and his opponents. al-Razi and Al-Farabi had provided methodology and knowledge in medicine and philosophy. Avicenna could use the great libraries of Balkh, Khwarezm, Gorgan, Rey, Isfahan and Hamedan. As various texts, such as the 'Ahd with Bahmanyar show, he debated philosophical points with the greatest scholars of the time. As Aruzi Samarqandi describes in his four articles before Avicenna left Khwarezm he had met al-Biruni (a noted scientist and astronomer), Abu Nasr Iraqi (a renowned mathematician), Abu Sahl Masihi (a respected philosopher) and Abu al-Khayr Khammar (a great physician).
|The Canon of Medicine|
|The Book of Healing|
|Hayy ibn Yaqdhan|
|Criticism of Avicennian philosophy|
He was born in Persia around 980 in Afshana, in Bukhara province, his mother's home, a small city now part of Uzbekistan. His father, a respected Ismaili  scholar of Balkh, an important town of the Persian state of Khorasan a part of Afghanistan, was at the time of his son's birth the governor in one of the Samanid Nuh ibn Mansur's estates. He had his son very carefully educated at Bukhara. Ibn Sina himself was a Twelver Shia. Ibn Sina's independent thought was served by an extraordinary intelligence and memory, which allowed him to overtake his teachers at the age of fourteen. As he said in his autobiography there wasn't anything which he hadn't learned when he reached eighteen.
Ibn Sīnā was put under the charge of a tutor, and his precocity soon made him the marvel of his neighbours; he displayed exceptional intellectual behaviour and was a child prodigy who had memorized the Qur'an by the age of 10 and a great deal of Persian poetry as well. He learned Indian arithmetic from an Indian greengrocer, and he began to learn more from a wandering scholar who gained a livelihood by curing the sick and teaching the young. He also studied Fiqh (Islamic jurisprudence) under the Hanafi scholar Ismail al-Zahid.
As a teenager, he was greatly troubled by the Metaphysics of Aristotle, which he could not understand until he read al-Farabi's commentary on the work. For the next year and a half, he studied philosophy, in which he encountered greater obstacles. In such moments of baffled inquiry, he would leave his books, perform the requisite ablutions (wudu), then go to the mosque, and continue in prayer (salah) till light broke on his difficulties. Deep into the night he would continue his studies, and even in his dreams problems would pursue him and work out their solution. Forty times, it is said, he read through the Metaphysics of Aristotle, till the words were imprinted on his memory; but their meaning was hopelessly obscure, until one day they found illumination, from the little commentary by Farabi, which he bought at a bookstall for the small sum of three dirhams. So great was his joy at the discovery, thus made by help of a work from which he had expected only mystery, that he hastened to return thanks to God, and bestowed alms upon the poor.
He turned to medicine at 16, and not only learned medical theory, but also by gratuitous attendance of the sick had, according to his own account, discovered new methods of treatment. The teenager achieved full status as a qualified physician at age 18, and found that "Medicine is no hard and thorny science, like mathematics and metaphysics, so I soon made great progress; I became an excellent doctor and began to treat patients, using approved remedies." The youthful physician's fame spread quickly, and he treated many patients without asking for payment.
His first appointment was that of physician to the emir, who owed him his recovery from a dangerous illness (997). Ibn Sina's chief reward for this service was access to the royal library of the Samanids, well-known patrons of scholarship and scholars. When the library was destroyed by fire not long after, the enemies of Ibn Sina accused him of burning it, in order for ever to conceal the sources of his knowledge. Meanwhile, he assisted his father in his financial labours, but still found time to write some of his earliest works.
When Ibn Sina was 22 years old, he lost his father. The Samanid dynasty came to its end in December 1004. Ibn Sina seems to have declined the offers of Mahmud of Ghazni, and proceeded westwards to Urgench in the modern Uzbekistan, where the vizier, regarded as a friend of scholars, gave him a small monthly stipend. The pay was small, however, so Ibn Sina wandered from place to place through the districts of Nishapur and Merv to the borders of Khorasan, seeking an opening for his talents. Shams al-Ma'äli Kavuus, the generous ruler of Dailam and central Persia, himself a poet and a scholar, with whom Ibn Sina had expected to find an asylum, was about that date (1052) starved to death by his troops who had revolted. Ibn Sina himself was at this season stricken down by a severe illness. Finally, at Gorgan, near the Caspian Sea, Ibn Sina met with a friend, who bought a dwelling near his own house in which Ibn Sina lectured on logic and astronomy. Several of Ibn Sina's treatises were written for this patron; and the commencement of his Canon of Medicine also dates from his stay in Hyrcania.
Ibn Sina subsequently settled at Rai, in the vicinity of modern Tehran, (present day capital of Iran), the home town of Rhazes; where Majd Addaula, a son of the last Buwayhid emir, was nominal ruler under the regency of his mother (Seyyedeh Khatun). About thirty of Ibn Sina's shorter works are said to have been composed in Rai. Constant feuds which raged between the regent and her second son, Shams al-Daula, however, compelled the scholar to quit the place. After a brief sojourn at Qazvin he passed southwards to Hamadãn where Shams al-Daula, another Buwayhid emir, had established himself. At first, Ibn Sina entered into the service of a high-born lady; but the emir, hearing of his arrival, called him in as medical attendant, and sent him back with presents to his dwelling. Ibn Sina was even raised to the office of vizier. The emir consented that he should be banished from the country. Ibn Sina, however, remained hidden for forty days in a sheikh Ahmed Fadhel's house, until a fresh attack of illness induced the emir to restore him to his post. Even during this perturbed time, Ibn Sina persevered with his studies and teaching. Every evening, extracts from his great works, the Canon and the Sanatio, were dictated and explained to his pupils. On the death of the emir, Ibn Sina ceased to be vizier and hid himself in the house of an apothecary, where, with intense assiduity, he continued the composition of his works.
Meanwhile, he had written to Abu Ya'far, the prefect of the dynamic city of Isfahan, offering his services. The new emir of Hamadan, hearing of this correspondence and discovering where Ibn Sina was hidden, incarcerated him in a fortress. War meanwhile continued between the rulers of Isfahan and Hamadãn; in 1024 the former captured Hamadan and its towns, expelling the Tajik mercenaries. When the storm had passed, Ibn Sina returned with the emir to Hamadan, and carried on his literary labours. Later, however, accompanied by his brother, a favourite pupil, and two slaves, Ibn Sina escaped out of the city in the dress of a Sufi ascetic. After a perilous journey, they reached Isfahan, receiving an honourable welcome from the prince.
Later life and Death
The remaining ten or twelve years of Ibn Sīnā's life were spent in the service of Abu Ja'far 'Ala Addaula, whom he accompanied as physician and general literary and scientific adviser, even in his numerous campaigns.
During these years he began to study literary matters and philology, instigated, it is asserted, by criticisms on his style. He contrasts with the nobler and more intellectual character of Averroes. A severe colic, which seized him on the march of the army against Hamadan, was checked by remedies so violent that Ibn Sina could scarcely stand. On a similar occasion the disease returned; with difficulty he reached Hamadan, where, finding the disease gaining ground, he refused to keep up the regimen imposed, and resigned himself to his fate.
His friends advised him to slow down and take life moderately. He refused, however, stating that: "I prefer a short life with width to a narrow one with length". On his deathbed remorse seized him; he bestowed his goods on the poor, restored unjust gains, freed his slaves, and every third day till his death listened to the reading of the Qur'an. He died in June 1037, in his fifty-eighth year, and was buried in Hamedan, Iran.
Medicine and pharmacology
Though the threads which comprise Unani healing can be traced all the way back to Claudius Galenus of Pergamum, who lived in the second century of the Christian Era, the basic knowledge of Unani medicine as a healing system was developed by Hakim Ibn Sina in his medical encyclopedia The Canon of Medicine. The time of origin is thus dated at circa 1025 AD, when Avicenna wrote The Canon of Medicine in Persia. While he was primarily influenced by Greek and Islamic medicine, he was also influenced by the Indian medical teachings of Sushruta and Charaka.
 The Canon of Medicine
About 100 treatises were ascribed to Ibn Sina. Some of them are tracts of a few pages, others are works extending through several volumes. The best-known amongst them, and that to which Ibn Sina owed his European reputation, is his 14-volume The Canon of Medicine, which was a standard medical text in Europe and the Islamic world up until the 18th century. The book is known for its introduction of systematic experimentation and quantification into the study of physiology, the discovery of contagious diseases and sexually transmitted diseases, the introduction of quarantine to limit the spread of infectious diseases, the introduction of experimental medicine, clinical trials, neuropsychiatry, risk factor analysis, and the idea of a syndrome in the diagnosis of specific diseases, and hypothesized the existence of microrganisms. It classifies and describes diseases, and outlines their assumed causes. Hygiene, simple and complex medicines, and functions of parts of the body are also covered. In this, Ibn Sīnā is credited as being the first to correctly document the anatomy of the human eye, along with descriptions of eye afflictions such as cataracts. It asserts that tuberculosis was contagious, which was later disputed by Europeans, but turned out to be true. It also describes the symptoms and complications of diabetes. Both forms of facial paralysis were described in-depth. In addition, the workings of the heart as a valve are described.
The Canon of Medicine was the first book dealing with experimental medicine, evidence-based medicine, randomized controlled trials, and efficacy tests, and it laid out the following rules and principles for testing the effectiveness of new drugs and medications, which still form the basis of clinical pharmacology and modern clinical trials:
- "The drug must be free from any extraneous accidental quality."
- "It must be used on a simple, not a composite, disease."
- "The drug must be tested with two contrary types of diseases, because sometimes a drug cures one disease by Its essential qualities and another by its accidental ones."
- "The quality of the drug must correspond to the strength of the disease. For example, there are some drugs whose heat is less than the coldness of certain diseases, so that they would have no effect on them."
- "The time of action must be observed, so that essence and accident are not confused."
- "The effect of the drug must be seen to occur constantly or in many cases, for if this did not happen, it was an accidental effect."
- "The experimentation must be done with the human body, for testing a drug on a lion or a horse might not prove anything about its effect on man."
An Arabic edition of the Canon appeared at Rome in 1593, and a Hebrew version at Naples in 1491. Of the Latin version there were about thirty editions, founded on the original translation by Gerard de Sabloneta. In the 15th century a commentary on the text of the Canon was composed. Other medical works translated into Latin are the Medicamenta Cordialia, Canticum de Medicina, and the Tractatus de Syrupo Acetoso.
It was mainly accident which determined that from the 12th to the 18th century, Ibn Sīnā should be the guide of medical study in European universities, and eclipse the names of Rhazes, Ali ibn al-Abbas and Averroes. His work is not essentially different from that of his predecessor Rhazes, because he presented the doctrine of Galen, and through Galen the doctrine of Hippocrates, modified by the system of Aristotle, as well as the Indian doctrines of Sushruta and Charaka. But the Canon of Ibn Sīnā is distinguished from the Al-Hawi (Continens) or Summary of Rhazes by its greater method, due perhaps to the logical studies of the former.
The work has been variously appreciated in subsequent ages, some regarding it as a treasury of wisdom, and others, like Averroes, holding it useful only as waste paper. In modern times it has been mainly of historic interest as most of its tenets have been disproved or expanded upon by scientific medicine. The vice of the book is excessive classification of bodily faculties, and over-subtlety in the discrimination of diseases. It includes five books; of which the first and second discuss physiology, pathology and hygiene, the third and fourth deal with the methods of treating disease, and the fifth describes the composition and preparation of remedies. This last part contains some personal observations.
He is ample in the enumeration of symptoms, and is said to be inferior in practical medicine and surgery. He introduced into medical theory the four causes of the Peripatetic system. Of natural history and botany he pretended to no special knowledge. Up to the year 1650, or thereabouts, the Canon was still used as a textbook in the universities of Leuven and Montpellier.
In the museum at Bukhara, there are displays showing many of his writings, surgical instruments from the period and paintings of patients undergoing treatment. Ibn Sīnā was interested in the effect of the mind on the body, and wrote a great deal on psychology, likely influencing Ibn Tufayl and Ibn Bajjah. He also introduced medical herbs.
Avicenna extended the theory of temperaments in The Canon of Medicine to encompass "emotional aspects, mental capacity, moral attitudes, self-awareness, movements and dreams." He summarized his version of the four humours and temperaments in a table as follows:
|Morbid states||inflammations become febrile||fevers related to serious humour, rheumatism||lassitude||loss of vigour|
|Functional power||deficient energy||deficient digestive power||difficult digestion|
|Subjective sensations||bitter taste, excessive thirst, burning at cardia||Lack of desire for fluids||mucoid salivation, sleepiness||insomnia, wakefulness|
|Physical signs||high pulse rate, lassitude||flaccid joints||diarrhea, swollen eyelids, rough skin, acquired habit||rough skin, acquired habit|
|Foods & medicines||calefacients harmful, infrigidants beneficial||infrigidants harmful, calefacients beneficial||moist articles harmful||dry regimen harmful, humectants beneficial|
|Relation to weather||worse in summer||worse in winter||bad in autumn|
In Muslim psychology and the neurosciences, Avicenna was a pioneer of neuropsychiatry. He first described numerous neuropsychiatric conditions, including hallucination, insomnia, mania, nightmare, melancholia, dementia, epilepsy, paralysis, stroke, vertigo and tremor.
Avicenna was also a pioneer in psychophysiology and psychosomatic medicine. He recognized 'physiological psychology' in the treatment of illnesses involving emotions, and developed a system for associating changes in the pulse rate with inner feelings, which is seen as an anticipation of the word association test attributed to Carl Jung. Avicenna is reported to have treated a very ill patient by "feeling the patient's pulse and reciting aloud to him the names of provinces, districts, towns, streets, and people." He noticed how the patient's pulse increased when certain names were mentioned, from which Avicenna deduced that the patient was in love with a girl whose home Avicenna was "able to locate by the digital examination." Avicenna advised the patient to marry the girl he is in love with, and the patient soon recovered from his illness after his marriage.
Avicenna's legacy in classical psychology is primarily embodied in the Kitab al-nafs parts of his Kitab al-shifa' (The Book of Healing) and Kitab al-najat (The Book of Deliverance). These were known in Latin under the title De Anima (treatises "on the soul"). The main thesis of these tracts is represented in his so-called "flying man" argument, which resonates with what was centuries later entailed by Descartes's cogito argument (or what phenomenology designates as a form of an "epoche").
In the The Canon of Medicine, Avicenna dealt with neuropsychiatry and described a number of neuropsychiatric conditions, including melancholia. He described melancholia as a depressive type of mood disorder in which the person may become suspicious and develop certain types of phobias.
Astronomy and astrology
The study of astrology was refuted by Avicenna. His reasons were both due to the methods used by astrologers being conjectural rather than empirical and also due to the views of astrologers conflicting with orthodox Islam. He also cited passages from the Qur'an in order to justify his refutation of astrology on both scientific and religious grounds.
- Liber Aboali Abincine de Anima in arte Alchemiae
- Declaratio Lapis physici Avicennae filio sui Aboali
- Avicennae de congelatione et conglutinatione lapifum
- Avicennae ad Hasan Regem epistola de Re recta
"Those of the chemical craft know well that no change can be effected in the different species of substances, though they can produce the appearance of such change."
In another work, translated into Latin as De congelatione et conglutinatione lapidum, Ibn Sina proposed a four-part classification of inorganic bodies, which was a significant improvement over the two-part classification of Aristotle (into orycta and metals) and three-part classification of Galen (into terrae, lapides and metals). The four parts of Ibn Sina's classification were: lapides, sulfur, salts and metals.
Ibn Sīnā wrote on Earth sciences such as geology in The Book of Healing, in which he developed the concept of uniformitarianism and law of superposition in geology. While discussing the formation of mountains, he explained:
"Either they are the effects of upheavals of the crust of the earth, such as might occur during a violent earthquake, or they are the effect of water, which, cutting itself a new route, has denuded the valleys, the strata being of different kinds, some soft, some hard... It would require a long period of time for all such changes to be accomplished, during which the mountains themselves might be somewhat diminished in size."
In mechanics, Ibn Sīnā developed an elaborate theory of motion, in which he made a distinction between the inclination (tendency to motion) and force of a projectile, and concluded that motion was a result of an inclination (mayl) transferred to the projectile by the thrower, and that projectile motion in a vacuum would not cease. He viewed inclination as a permanent force whose effect is dissipated by external forces such as air resistance. His theory of motion was thus consistent with the concept of inertia in Newton's first law of motion. Ibn Sīnā also referred to mayl to as being proportional to weight times velocity, a precursor to the concept of momentum in Newton's second law of motion. Ibn Sīnā's theory of mayl was further developed by Jean Buridan in his theory of impetus.
In optics, Ibn Sina reasoned that the speed of light is finite, as he "observed that if the perception of light is due to the emission of some sort of particles by a luminous source, the speed of light must be finite." He also provided a sophisticated explanation for the rainbow phenomenon. Carl Benjamin Boyer described Ibn Sīnā's theory on the rainbow as follows:
"Independent observation had demonstrated to him that the bow is not formed in the dark cloud but rather in the very thin mist lying between the cloud and the sun or observer. The cloud, he thought, serves simply as the background of this thin substance, much as a quicksilver lining is placed upon the rear surface of the glass in a mirror. Ibn Sīnā would change the place not only of the bow, but also of the color formation, holding the iridescence to be merely a subjective sensation in the eye."
Ibn Sīnā wrote extensively on early Islamic philosophy, especially the subjects logic, ethics, and metaphysics, including treatises named Logic and Metaphysics. Most of his works were written in Arabic - which was the de facto scientific language of that time, and some were written in the Persian language. Of linguistic significance even to this day are a few books that he wrote in nearly pure Persian language (particularly the Danishnamah-yi 'Ala', Philosophy for Ala' ad-Dawla'). Ibn Sīnā's commentaries on Aristotle often corrected the philosopher, encouraging a lively debate in the spirit of ijtihad.
In the medieval Islamic world, due to Avicenna's successful reconciliation between Aristotelianism and Neoplatonism along with Kalam, Avicennism eventually became the leading school of Islamic philosophy by the 12th century, with Avicenna becoming a central authority on philosophy.
Avicennism was also influential in medieval Europe, particular his doctrines on the nature of the soul and his existence-essence distinction, along with the debates and censure that they raised in scholastic Europe. This was particularly the case in Paris, where Avicennism was later proscribed in 1210. Nevertheless, his psychology and theory of knowledge influenced William of Auvergne and Albertus Magnus, while his metaphysics had an impact on the thought of Thomas Aquinas.
Early Islamic philosophy, imbued as it is with Islamic theology, distinguishes more clearly than Aristotelianism the difference between essence and existence. Whereas existence is the domain of the contingent and the accidental, essence endures within a being beyond the accidental. The philosophy of Ibn Sīnā, particularly that part relating to metaphysics, owes much to al-Farabi. The search for a truly definitive Islamic philosophy can be seen in what is left to us of his work.
Following al-Farabi's lead, Avicenna initiated a full-fledged inquiry into the question of being, in which he distinguished between essence (Mahiat) and existence (Wujud). He argued that the fact of existence can not be inferred from or accounted for by the essence of existing things and that form and matter by themselves cannot interact and originate the movement of the universe or the progressive actualization of existing things. Existence must, therefore, be due to an agent-cause that necessitates, imparts, gives, or adds existence to an essence. To do so, the cause must be an existing thing and coexist with its effect. 
Avicenna’s consideration of the essence-attributes question may be elucidated in terms of his ontological analysis of the modalities of being; namely impossibility, contingency, and necessity. Avicenna argued that the impossible being is that which cannot exist, while the contingent in itself (mumkin bi-dhatihi) has the potentiality to be or not to be without entailing a contradiction. When actualized, the contingent becomes a ‘necessary existent due to what is other than itself’ (wajib al-wujud bi-ghayrihi). Thus, contingency-in-itself is potential beingness that could eventually be actualized by an external cause other than itself. The metaphysical structures of necessity and contingency are different. Necessary being due to itself (wajib al-wujud bi-dhatihi) is true in itself, while the contingent being is ‘false in itself’ and ‘true due to something else other than itself’. The necessary is the source of its own being without borrowed existence. It is what always exists.  The Necessary exists ‘due-to-Its-Self’, and has no quiddity/essence (mahiyya) other than existence (wujud). Furthermore, It is ‘One’ (wahid ahad)  since there cannot be more than one ‘Necessary-Existent-due-to-Itself’ without differentia (fasl) to distinguish them from each other. Yet, to require differentia entails that they exist ‘due-to-themselves’ as well as ‘due to what is other than themselves’; and this is contradictory. However, if no differentia distinguishes them from each other, then there is no sense in which these ‘Existents’ are not one and the same.  Avicenna adds that the ‘Necessary-Existent-due-to-Itself’ has no genus (jins), nor a definition (hadd), nor a counterpart (nadd), nor an opposite (did), and is detached (bari’) from matter (madda), quality (kayf), quantity (kam), place (ayn), situation (wad’), and time (waqt). 
Avicenna discussed the topic of logic in Islamic philosophy extensively in his works, and developed his own system of logic known as "Avicennian logic" as an alternative to Aristotelian logic. By the 12th century, Avicennian logic had replaced Aristotelian logic as the dominant system of logic in the Islamic world. After the Latin translations of the 12th century, Avicennian logic was also influential in Europe.
Ibn Sina developed an early theory on hypothetical syllogism, which formed the basis of his early risk factor analysis. He also developed an early theory on propositional calculus, which was an area of logic not covered in the Aristotelian tradition. The first criticisms of Aristotelian logic were also written by Ibn Sina, who developed an original theory on temporal modal syllogism. Ibn Sina also contributed inventively to the development of inductive logic, being the first to describe the methods of agreement, difference and concomitant variation which are critical to inductive logic and the scientific method.
Ibn Sina and Abū Rayhān al-Bīrūnī engaged in a written debate, with al-Biruni mostly criticizing Aristotelian natural philosophy and the Peripatetic school, while Avicenna and his student Ahmad ibn 'Ali al-Ma'sumi respond to al-Biruni's criticisms in writing. Al-Biruni began by asking Avicenna eighteen questions, ten of which were criticisms of Aristotle's On the Heavens.
Philosophy of science
In the Al-Burhan (On Demonstration) section of The Book of Healing, Avicenna discussed the philosophy of science and described an early scientific method of inquiry. He discusses Aristotle's Posterior Analytics and significantly diverged from it on several points. Avicenna discussed the issue of a proper methodology for scientific inquiry and the question of "How does one acquire the first principles of a science?" He asked how a scientist would arrive at "the initial axioms or hypotheses of a deductive science without inferring them from some more basic premises?" He explains that the ideal situation is when one grasps that a "relation holds between the terms, which would allow for absolute, universal certainty." Avicenna then adds two further methods for arriving at the first principles: the ancient Aristotelian method of induction (istiqra), and the method of examination and experimentation (tajriba). Avicenna criticized Aristotelian induction, arguing that "it does not lead to the absolute, universal, and certain premises that it purports to provide." In its place, he develops a "method of experimentation as a means for scientific inquiry."
Ibn Sīnā was a devout Muslim and sought to reconcile rational philosophy with Islamic theology. His aim was to prove the existence of God and his creation of the world scientifically and through reason and logic. Avicenna wrote a number of treatises dealing with Islamic theology. These included treatises on the Islamic prophets, whom he viewed as "inspired philosophers", and on various scientific and philosophical interpretations of the Qur'an, such as how Quranic cosmology corresponds to his own philosophical system.
Ibn Sīnā memorized the Qur'an by the age of seven, and as an adult, he wrote five treatises commenting on suras from the Qur'an. One of these texts included the Proof of Prophecies, in which he comments on several Quranic verses and holds the Qur'an in high esteem. Avicenna argued that the Islamic prophets should be considered higher than philosophers.
While he was imprisoned in the castle of Fardajan near Hamadhan, Avicenna wrote his famous "Floating Man" thought experiment to demonstrate human self-awareness and the substantiality of the soul. He referred to the living human intelligence, particularly the active intellect, which he believed to be the hypostasis by which God communicates truth to the human mind and imparts order and intelligibility to nature. His "Floating Man" thought experiment tells its readers to imagine themselves suspended in the air, isolated from all sensations, which includes no sensory contact with even their own bodies. He argues that, in this scenario, one would still have self-consciousness. He thus concludes that the idea of the self is not logically dependent on any physical thing, and that the soul should not be seen in relative terms, but as a primary given, a substance.
In the chapters on mechanics and engineering in his encyclopedia Mi'yar al-'aql (The Measure of the Mind), Avicenna writes an analysis on the ilm al-hiyal (science of ingenious devices) and makes the first successful attempt to classify simple machines and their combinations. He first describes and illustrates the five constituent simple machines: the lever, pulley, screw, wedge, and windlass. He then analyzes all the combinations of these simple machines, such as the windlass-screw, windlass-pulley and windlass-lever for example. He is also the first to describe a mechanism which is essentially a combination of all of these simple machines (except for the wedge).
Almost half of Ibn Sīnā's works are versified. His poems appear in both Arabic and Persian. As an example, Edward Granville Browne claims that the following verses are incorrectly attributed to Omar Khayyám, and were originally written by Ibn Sīnā:
از قعر گل سیاه تا اوج زحل,
Up from Earth's Centre through the Seventh Gate
کردم همه مشکلات گیتی را حل,
I rose, and on the Throne of Saturn sate,
بیرون جستم زقید هر مکر و حیل,
And many Knots unravel'd by the Road;
هر بند گشاده شد مگر بند اجل.
But not the Master-Knot of Human Fate.
When some of his opponents blame him for blasphemy, he says 
کفر چو منی گزاف و آسان نبود
The blasphemy of somebody like me is not easy and exorbitant
محکمتر از ایمان من ایمان نبود
There isn't any stronger faith than my faith
در دهر چو من یکی و آن هم کافر
If there is just one person like me in the world and that one is impious
پس در همه دهر یک مسلمان نبود
So there are no Muslims in the whole world.
- Further information: Avicennism
As early as the 1300s when Dante Alighieri showed him experiencing a perfect eternity with some the greatest men in history in his Divine Comedy such as Virgil, Averroes, Homer, Horace, Ovid, Lucan, Socrates, Plato, and Saladin, Avicenna has been recognized by both East and West, as one of history's great figures.
George Sarton, the father of the history of science, described Ibn Sīnā as "one of the greatest thinkers and medical scholars in history" and called him "the most famous scientist of Islam and one of the most famous of all races, places, and times." He was one of the Islamic world's leading writers in the field of medicine. He was influenced by the approach of Hippocrates and Galen, as well as Sushruta and Charaka. Along with Rhazes, Abulcasis, Ibn al-Nafis, and al-Ibadi, Ibn Sīnā is considered an important compiler of early Muslim medicine. He is remembered in Western history of medicine as a major historical figure who made important contributions to medicine and the European Renaissance. Ibn Sīnā is also considered the father of the fundamental concept of momentum in physics.
In Iran, he is considered a national icon, and is often regarded as one of the greatest Persians to have ever lived. Many portraits and statues remain in Iran today. An impressive monument to the life and works of the man who is known as the 'doctor of doctors' still stands outside the Bukhara museum and his portrait hangs in the Hall of the Avicenna Faculty of Medicine in the University of Paris. There is also a crater on the moon named the Avicenna crater. Bu-Ali Sina University in Hamedan (Iran), the ibn Sīnā Tajik State Medical University in Dushanbe (The capital of the Republic of Tajikistan), Avicenna School in Karachi, Pakistan and Ibne Sina Balkh Medical School in his native province of Balkh in Afghanistan are all named in his honour.
In 1980, the former Soviet Union, which then ruled his birthplace Bukhara, celebrated the thousandth anniversary of Avicenna's birth by circulating various commemorative stamps with artistic illustrations, and by erecting a bust of Avicenna based on anthropological research by Soviet scholars.
In March 2008, it was announced  that Avicenna’s name would be used for new Directories of education institutions for health care professionals, worldwide. The Avicenna Directories will list universities and schools where doctors, public health practitioners, pharmacists and others, are educated. The project team stated “Why Avicenna? Avicenna … was … noted for his synthesis of knowledge from both east and west. He has had a lasting influence on the development of medicine and health sciences. The use of Avicenna’s name symbolises the worldwide partnership that is needed for the promotion of health services of high quality.”
Scarcely any member of the Muslim circle of the sciences, including theology, philology, mathematics, astronomy, physics, and music, was left untouched by the treatises of Ibn Sīnā. This vast quantity of works - be they full-blown treatises or opuscula - vary so much in style and content (if one were to compare between the 'ahd made with his disciple Bahmanyar to uphold philosophical integrity with the Provenance and Direction, for example) that Yahya (formerly Jean) Michot has accused him of "neurological bipolarity".
Ibn Sīnā's works numbered almost 450 volumes on a wide range of subjects, of which around 240 have survived. In particular, 150 volumes of his surviving works concentrate on philosophy and 40 of them concentrate on medicine. His most famous works are The Book of Healing, a vast philosophical and scientific encyclopaedia, and The Canon of Medicine,
Ibn Sīnā wrote at least one treatise on alchemy, but several others have been falsely attributed to him. His book on animals was translated by Michael Scot. His Logic, Metaphysics, Physics, and De Caelo, are treatises giving a synoptic view of Aristotelian doctrine, though the Metaphysics demonstrates a significant departure from the brand of Neoplatonism known as Aristotelianism in Ibn Sīnā's world; Arabic philosophers have hinted at the idea that Ibn Sīnā was attempting to "re-Aristotelianise" Muslim philosophy in its entirety, unlike his predecessors, who accepted the conflation of Platonic, Aristotelian, Neo- and Middle-Platonic works transmitted into the Muslim world.
The Logic and Metaphysics have been printed more than once, the latter, e.g., at Venice in 1493, 1495, and 1546. Some of his shorter essays on medicine, logic, etc., take a poetical form (the poem on logic was published by Schmoelders in 1836). Two encyclopaedic treatises, dealing with philosophy, are often mentioned. The larger, Al-Shifa' (Sanatio), exists nearly complete in manuscript in the Bodleian Library and elsewhere; part of it on the De Anima appeared at Pavia (1490) as the Liber Sextus Naturalium, and the long account of Ibn Sina's philosophy given by Muhammad al-Shahrastani seems to be mainly an analysis, and in many places a reproduction, of the Al-Shifa'. A shorter form of the work is known as the An-najat (Liberatio). The Latin editions of part of these works have been modified by the corrections which the monastic editors confess that they applied. There is also a حكمت مشرقيه (hikmat-al-mashriqqiyya, in Latin Philosophia Orientalis), mentioned by Roger Bacon, the majority of which is lost in antiquity, which according to Averroes was pantheistic in tone.
List of Works
This is the list of some of Avicenna's well-known works:
- Sirat al-shaykh al-ra’is (The Life of Ibn Sina), ed. and trans. WE. Gohlman, Albany, NY: State University of New York Press, 1974. (The only critical edition of Ibn Sina’s autobiography, supplemented with material from a biography by his student Abu ‘Ubayd al-Juzjani. A more recent translation of the Autobiography appears in D. Gutas, Avicenna and the Aristotelian Tradition: Introduction to Reading Avicenna’s Philosophical Works, Leiden: Brill, 1988.)
- Al-Isharat wa-‘l-tanbihat (Remarks and Admonitions), ed. S. Dunya, Cairo, 1960; parts translated by S.C. Inati, Remarks and Admonitions, Part One: Logic, Toronto, Ont.: Pontifical Institute for Mediaeval Studies, 1984, and Ibn Sina and Mysticism, Remarks and Admonitions: Part 4, London: Kegan Paul International, 1996. 
- Al-Qanun fi’l-tibb (The Canon of Medicine), ed. I. a-Qashsh, Cairo, 1987. (Encyclopedia of medicine.)
- Risalah fi sirr al-qadar (Essay on the Secret of Destiny), trans. G. Hourani in Reason and Tradition in Islamic Ethics, Cambridge: Cambridge University Press, 1985. 
- Danishnama-i ‘ala’i (The Book of Scientific Knowledge), ed. and trans. P Morewedge, The Metaphysics of Avicenna, London: Routledge and Kegan Paul, 1973. 
- Kitab al-Shifa’ (The Book of Healing). (Ibn Sina’s major work on philosophy. He probably began to compose al-Shifa’ in 1014, and completed it in 1020.) Critical editions of the Arabic text have been published in Cairo, 1952-83, originally under the supervision of I. Madkour
- Hayy ibn Yaqdhan a Persian myth. A novel called Hayy ibn Yaqdhan, based on Avicenna's story, was later written by Ibn Tufail (Abubacer) in the 12th century and translated into Latin and English as Philosophus Autodidactus in the 17th and 18th centuries respectively. In the 13th century, Ibn al-Nafis wrote his own novel Fadil ibn Natiq, known as Theologus Autodidactus in the West, as a critical response to Hayy ibn Yaqdhan.