In the history of medicine, Islamic medicine or Arabic medicine refers to medicine developed in the medieval Islamic civilisation and written in Arabic, the lingua franca of the Islamic civilization. Despite these names, a significant number of scientists during this period were not Arab. Lumping these scientists into narrow label of "Arab-Islamic" is historically inaccurate. This label does not appreciate the rich diversity of eastern scholars who have contributed to science in an era.
Islamic medicine was a genre of medical writing that was influenced by several different medical systems, including the traditional Arabian medicine of Muhammad's time, ancient Hellenistic medicine such as Unani, ancient Indian medicine such as Ayurveda, and the ancient Iranian Medicine of the Academy of Gundishapur. Many early authors of Islamic medicine were usually clerics rather than physicians, and were known to have advocated the traditional medical practices of prophet Muhammad's time, such as those mentioned in the Qur'an and Hadith. For instance, therapy did not require a patient to undergo any surgical procedures at the time. From the 9th century, Hunayn ibn Ishaq translated a number of Galen's works into the Arabic language, followed by translations of the Sushruta Samhita, Charaka Samhita and Middle Persian works from Gundishapur. Muslim physicians soon began making many of their own significant advances and contributions to the field of medicine, including the subjects of anatomy, bacteriology, microbiology, ophthalmology, pathology, pharmacology, pharmacy, physiology, psychology, surgery, and the pharmaceutical sciences.
Medicine was a central part of medieval Islamic culture. Responding to circumstances of time and place, Islamic physicians and scholars developed a large and complex medical literature exploring and synthesizing the theory and practice of medicine. Islamic medicine was initially built on tradition, chiefly the theoretical and practical knowledge developed in Persia, Greece, Rome, and India. Galen and Hippocrates were pre-eminent authorities, as well as the Indian physicians Sushruta and Charaka, and the Hellenistic scholars in Alexandria. Islamic scholars translated their voluminous writings from Greek and Sanskrit into Arabic and then produced new medical knowledge based on those texts. In order to make the Greek and Indian traditions more accessible, understandable, and teachable, Islamic scholars ordered and made more systematic the vast and sometimes inconsistent Greco-Roman and Indian medical knowledge by writing encyclopedias and summaries. It was through Arabic translations that the West learned of Hellenic medicine, including the works of Galen and Hippocrates. Of equal if not of greater influence in Western Europe were systematic and comprehensive works such as Avicenna's The Canon of Medicine, which were translated into Latin and then disseminated in manuscript and printed form throughout Europe. During the fifteenth and sixteenth centuries alone, The Canon of Medicine was published more than thirty-five times.
Muslim physicians set up some of the earliest dedicated hospitals. In the medieval Islamic world, hospitals were built in all major cities; in Cairo for example, the Qalawun Hospital could care for 8,000 patients, and a staff that included physicians, pharmacists, and nurses. One could also access a dispensary, and research facility that led to advances, which included the discovery of the contagious nature of diseases, and research into optics and the mechanisms of the eye. Muslim doctors were removing cataracts with hollow needles over 1000 years before Western physicians dared attempt such a task. Hospitals were built not only for the physically sick, but for the mentally sick also. One of the first ever psychiatric hospitals that cared for the mentally ill was built in Cairo. Hospitals later spread to Europe during the Crusades, inspired by the hospitals in the Middle East. The first hospital in Paris, Les Quinze-vingts, was founded by Louis IX after his return from the Crusade between 1254-1260.
Hospitals in the Islamic world featured competency tests for doctors, drug purity regulations, nurses and interns, and advanced surgical procedures. Hospitals were also created with separate wards for specific illnesses, so that people with contagious diseases could be kept away from other patients.
Razi (Rhazes) wrote the Comprehensive Book of Medicine in the 9th century. The Large Comprehensive was the most sought after of all his compositions, in which Rhazes recorded clinical cases of his own experience and provided very useful recordings of various diseases. The Comprehensive Book of Medicine, with its introduction of measles and smallpox, was very influential in Europe.
Ali ibn Abbas al-Majusi (Haly Abbas)'s Kitab Kamil as-sina'a at-tibbiyya ("Complete Book of the Medical Art"), c. 980, became better known as the Kitab al-Maliki ("Royal Book", Latin: Liber regalis) in honour of its royal patron 'Adud al-Dawla. In twenty sections, ten of theory and ten of practice, it was more systematic and concise than Razi's Hawi, but more practical than Avicenna's Canon, by which it was superseded. With many interpolations and substitutions, it served as the basis for the Pantegni (c. 1087) of Constantinus Africanus, the founding text of the Schola Medica Salernitana in Salerno.
Abu al-Qasim al-Zahrawi (Abulcasis), regarded as the father of modern surgery, contributed greatly to the discipline of medical surgery with his Kitab al-Tasrif ("Book of Concessions"), a 30-volume medical encyclopedia published in 1000, which was later translated to Latin and used in European medical schools for centuries. He invented numerous surgical instruments and described them in his al-Tasrif.
Avicenna, a Hanbali and Mu'tazili philosopher and doctor in the early 11th century, was another influential figure. He is regarded as the father of modern medicine, and one of the greatest thinkers and medical scholars in history. His medical encyclopedia, The Canon of Medicine (c. 1020), remained a standard textbook in Europe for centuries, up until the renewal of the Muslim tradition of scientific medicine. He also wrote The Book of Healing (actually a more general encyclopedia of science and philosophy), which became another popular textbook in Europe. Among other things, Avicenna's contributions to medicine include the introduction of systematic experimentation and quantification into the study of physiology, the 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, risk factor analysis, and the idea of a syndrome in the diagnosis of specific diseases, the first descriptions on bacteria and viral organisms, the distinction of mediastinitis from pleurisy, the contagious nature of phthisis and tuberculosis, the distribution of diseases by water and soil, and the first careful descriptions of skin troubles, sexually transmitted diseases, perversions, and nervous ailments, as well the use of ice to treat fevers, and the separation of medicine from pharmacology, which was important to the development of the pharmaceutical sciences.
Abū Rayhān al-Bīrūnī's Kitab-al-Saidana was an extensive medical encyclopedia which synthesized Islamic medicine with Indian medicine. His medical investigations included one of the earliest descriptions on Siamese twins.
One of the features in medieval Muslim hospitals that distinguished them from their contemporaries was their higher standards of medical ethics. Hospitals in the Islamic world treated patients of all religions, ethnicities, and backgrounds, while the hospitals themselves often employed staff from Christian, Jewish and other minority backgrounds. Muslim doctors and physicians were expected to have obligations towards their patients, regardless of their wealth or backgrounds. The ethical standards of Muslim physicians was first laid down in the 9th century by Ishaq bin Ali Rahawi, who wrote the Adab al-Tabib (Conduct of a Physician), the first treatise dedicated to medical ethics. He regarded physicians as "guardians of souls and bodies", and wrote twenty chapters on various topics related to medical ethics, including:
- What the physician must avoid and beware of
- The manners of visitors
- The care of remedies by the physician
- The dignity of the medical profession
- The examination of physicians
- The removal of corruption among physicians
The first documented description of a peer review process is found in the Ethics of the Physician written by Ishaq bin Ali al-Rahwi (854–931) of al-Raha, Syria, who describes the first medical peer review process. His work, as well as later Arabic medical manuals, state that a visiting physician must always make duplicate notes of a patient's condition on every visit. When the patient was cured or had died, the notes of the physician were examined by a local medical council of other physicians, who would review the practising physician's notes to decide whether his/her performance have met the required standards of medical care. If their reviews were negative, the practicing physician could face a lawsuit from a maltreated patient.
Like in other fields of science, Muslim physicians and doctors developed the first scientific methods for the field of medicine. This included the introduction of experimentation, quantification, experimental medicine, evidence-based medicine, clinical trials, dissection, animal testing, human experimentation and postmortem autopsy by Muslim physicians, whilst hospitals in the Islamic world featured the first drug tests, drug purity regulations, and competency tests for doctors.
In the 9th century, al-Kindi (Alkindus), in De Gradibus, demonstrated the application of mathematics to medicine, particularly in the field of pharmacology. This includes the development of a mathematical scale to quantify the strength of drugs, and a system that would allow a doctor to determine in advance the most critical days of a patient's illness, based on the phases of the Moon.
In the 10th century, Razi (Rhazes) introduced controlled experiment and clinical observation into the field of medicine, and rejected medical theories unverified by experimentation. The first known medical experiment was carried out by Razi in order to find the most hygienic place to build a hospital. He hung pieces of meat in places throughout 10th century Baghdad and observed where the meat decomposed least quickly, and that was where he built the hospital. In his Comprehensive Book of Medicine, Razi recorded clinical cases of his own experience and provided very useful recordings of various diseases. In his Doubts about Galen, Razi was also the first to prove both Galen's theory of humorism and Aristotle's theory of classical elements false using experimentation. He also introduced urinalysis and stool tests.
Avicenna (Ibn Sina) is considered the father of modern medicine, for his introduction of systematic experimentation and quantification into the study of physiology, the introduction of experimental medicine, clinical trials, risk factor analysis, and the idea of a syndrome in the diagnosis of specific diseases, the experimental use and testing of drugs, and a precise guide for practical experimentation in the process of discovering and proving the effectiveness of medical substances, in his medical encyclopedia, The Canon of Medicine (c. 1020), which 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."
The first physicians known to have performed human autopsies and postmortem dissections in their medical experiments were Ibn Zuhr (Avenzoar), Saladin's physician Ibn Jumay, Abd-el-latif, and Ibn al-Nafis.
"Through their medical investigations they not merely widened the horizons of medicine, but enlarged humanistic concepts generally. [...] Thus it can hardly have been accidental that those researches should have led them that were inevitably beyond the reach of Greek masters. If it is regarded as symbolic that the most spectacular achievement of the mid-twentieth century is atomic fission and the nuclear bomb, likewise it would not seem fortuitous that the early Muslim's medical endeavor should have led to a discovery that was quite as revolutionary though possibly more beneficent."
"A philosophy of self-centredness, under whatever disguise, would be both incomprehensible and reprehensible to the Muslim mind. That mind was incapable of viewing man, whether in health or sickness as isolated from God, from fellow men, and from the world around him. It was probably inevitable that the Muslims should have discovered that disease need not be born within the patient himself but may reach from outside, in other words, that they should have been the first to establish clearly the existence of contagion."
"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."
"We have reason to believe that when, during the crusades, Europe at last began to establish hospitals, they were inspired by the Arabs of near East.... The first hospital in Paris, Les Quinze-vingt, was founded by Louis IX after his return from the crusade 1254-1260."
Anatomy and physiology
In anatomy and physiology, the first physician to refute Galen's theory of humorism was Razi (Rhazes) in his Doubts about Galen in the 10th century. He criticized Galen's theory that the body possessed four separate "humors" (liquid substances), whose balance are the key to health and a natural body-temperature. Razi was the first to prove this theory wrong using an experimental method. He carried out an experiment which would upset this system by inserting a liquid with a different temperature into the body resulting in an increase or decrease of bodily heat, which resembled the temperature of that particular fluid. Razi noted particularly that a warm drink would heat up the body to a degree much higher than its own natural temperature, thus the drink would trigger a response from the body, rather than transferring only its own warmth or coldness to it. This line of criticism was the first comprehensive experimental refutation of Galen's theory of humours and Aristotle's theory of the four classical elements on which it was grounded. Razi's own chemical experiments suggested other qualities of matter, such as "oiliness" and "sulfurousness", or inflammability and salinity, which were not readily explained by the traditional fire, water, earth and air division of elements.
The contributions of Avicenna to physiology include the introduction of systematic experimentation and quantification into the study of physiology in The Canon of Medicine (c. 1020). The contributions of Ibn al-Haytham (Alhacen) to anatomy and physiology include his correct explanation of the process of sight and visual perception for the first time in his Book of Optics, published in 1021. Other innovations introduced by Muslim physicians to the field of physiology by this time include the use of animal testing.
Ibn Zuhr (Avenzoar) (1091-1161) was the first physician known to have made human autopsy and postmortem dissections. He proved that the skin disease scabies was caused by a parasite, a discovery which upset the theory of humorism supported by Hippocrates and Galen. The removal of the parasite from the patient's body did not involve purging, bleeding, or any other traditional treatments associated with the four humours.
In the 12th century, Saladin's physician Ibn Jumay was also one the first to undertake human postmortem dissections, and he made an explicit appeal for other physicians to do so as well. During a famine in Egypt in 1200, Abd-el-latif observed and examined a large number of skeletons, and he discovered that Galen was incorrect regarding the formation of the bones of the lower jaw and sacrum.
Ibn al-Nafis was another proponent of postmortem dissection, and in 1242, he was the first to describe human blood circulation and pulmonary circulation, for which he is considered the father of the theory of circulation. This discovery would be rediscovered, or perhaps merely demonstrated, by William Harvey in 1628, who was previously credited for this discovery in Western history.
The Arab physician Ibn al-Lubudi (1210-1267), also from Damascus, wrote the Collection of discussions relative to fifty psychological and medical questions, in which he rejects the theory of four humours supported by Galen and Hippocrates, discovers that the body and its preservation depend exclusively upon blood, rejects Galen's idea that women can produce sperm, and discovers that the movement of arteries are not dependant upon the movement of the heart, that the heart is the first organ to form in a fetus' body (rather than the brain as claimed by Hippocrates), and that the bones forming the skull can grow into tumors. He also advises that in cases of extreme fever, a patient should not be released from hospital.
Bacteriology, microbiology, pathology
Muslim physicians were responsible for the discovery of infectious disease and the immune system and the introduction of bacteriology, microbiology and pathology. Their discovery of contagious disease in particular is considered revolutionary and is one of the most important discoveries in medicine. Early ideas on contagion can be traced back to several hadiths attributed to Muhammad in the 7th century, who is said to have understood the contagious nature of leprosy, mange, and sexually transmitted disease. These early ideas on contagion arose from the generally sympathetic attitude of Muslim physicians towards lepers (who were often seen in a negative light in other ancient and medieval societies) which can be traced back through hadiths attributed to Muhammad and to the following advice given in the Qur'an:
"There is no fault in the blind, and there is no fault in the lame, and there is no fault in the sick."
The theory of contagious disease, however, was not fully understood until the time of Avicenna in the 11th century. By then, the pathology of contagion had been fully understood, and as a result, hospitals were created with separate wards for specific illnesses, so that people with contagious diseases could be kept away from other patients who do not have any contagious diseases.
In order to find the most hygienic place to build a hospital, Muhammad ibn Zakarīya Rāzi (Rhazes) carried out an experiment where he hung pieces of meat in places throughout 10th century Baghdad and observed where the meat decomposed least quickly. Razi also wrote the Comprehensive Book of Medicine in the 9th century. The Large Comprehensive was the most sought after of all his compositions, in which Razi recorded clinical cases of his own experience and provided very useful recordings of various diseases, as well as the discovery of measles and smallpox. The Large Comprehensive also criticized the views of Galen, after Razi had observed many clinical cases which did not follow Galen's descriptions of fevers. For example, he stated that Galen's descriptions of urinary ailments were inaccurate as he had only seen three cases, while Razi had studied hundreds of such cases in hospitals of Baghdad and Rayy. The Comprehensive Book of Medicine, especially with its introduction of measles and smallpox, was very influential in Europe.
In The Canon of Medicine (1020), Avicenna discovered the contagious nature of infectious diseases such as phthisis and tuberculosis, the distribution of diseases by water and soil, and the existence of sexually transmitted diseases, stated that bodily secretion is contaminated by foul foreign earthly bodies before being infected, gave the first descriptions on bacteria and viral organisms (though he did not view them as primary causes of disease), and introduced quarantine as a means of limiting the spread of contagious diseases.
When the Black Death bubonic plague reached al-Andalus in the 14th century, Ibn Khatima discovered that infectious diseases are caused by microorganisms which enter the human body. Another 14th century Andalusian physician, Ibn al-Khatib (1313-1374), wrote a treatise called On the Plague, in which he stated:
"The existence of contagion is established by experience, investigation, the evidence of the senses and trustworthy reports. These facts constitute a sound argument. The fact of infection becomes clear to the investigator who notices how he who establishes contact with the aftlicted gets the disease, whereas he who is not in contact remains safe, and how transmission is affected through garments, vessels and earrings."
Of all the branches of Islamic medicine, ophthalmology was one of the foremost. The specialized instruments used in their operations ran into scores. Innovations such as the “injection syringe”, a hollow needle, invented by Ammar ibn Ali of Mosul, which was used for the extraction by suction of soft cataracts were quite common.
Al-Kindi was a renowned 9th century Arab doctor who wrote many books on the subject of medicine. His most important work in the field was De Gradibus, in which he demonstrated the application of mathematics to medicine, particularly in the field of pharmacology. This includes the development of a mathematical scale to quantify the strength of drugs, and a system that would allow a doctor to determine in advance the most critical days of a patient's illness, based on the phases of the Moon.
In his Comprehensive Book of Medicine, Razi (Rhazes) recorded clinical cases of his own experience and provided very useful recordings of various diseases. The Comprehensive Book of Medicine, with its introduction of measles and smallpox, was very influential in Europe. Razi also carried out an experiment in order to find the most hygienic place to build a hospital. He hung pieces of meat in places throughout 10th century Baghdad and observed where the meat decomposed least quickly, and that was where he built his hospital.
Avicenna's contribution to the pharmaceutical sciences include the introduction of systematic experimentation and quantification into pharmacology and the study of physiology in The Canon of Medicine (1020s), the introduction of experimental medicine, evidence-based medicine, clinical trials, randomized controlled trials, efficacy tests, and clinical pharmacology, and the first careful descriptions of skin troubles, sexually transmitted diseases, perversions, and nervous ailments, as well the use of ice to treat fevers, and the separation of medicine from pharmacology, which was important to the development of the pharmaceutical sciences.
The advances made in the Middle East by Muslim chemists in botany and chemistry led Muslim physicians to substantially develop pharmacology. Muhammad ibn Zakarīya Rāzi (Rhazes) (865-915), for instance, acted to promote the medical uses of chemical compounds. Abu al-Qasim al-Zahrawi (Abulcasis) (936-1013) pioneered the preparation of medicines by sublimation and distillation. His Liber servitoris is of particular interest, as it provides the reader with recipes and explains how to prepare the `simples’ from which were compounded the complex drugs then generally used. Sabur Ibn Sahl (d 869), was, however, the first physician to initiate pharmacopoedia, describing a large variety of drugs and remedies for ailments. Al-Biruni (973-1050) wrote one of the most valuable Islamic works on pharmacology entitled Kitab al-Saydalah (The Book of Drugs), where he gave detailed knowledge of the properties of drugs and outlined the role of pharmacy and the functions and duties of the pharmacist. Ibn Sina (Avicenna), too, described no less than 700 preparations, their properties, mode of action and their indications. He devoted in fact a whole volume to simple drugs in The Canon of Medicine. Of great impact were also the works by al-Maridini of Baghdad and Cairo, and Ibn al-Wafid (1008-1074), both of which were printed in Latin more than fifty times, appearing as De Medicinis universalibus et particularibus by `Mesue' the younger, and the Medicamentis simplicibus by `Abenguefit'. Peter of Abano (1250-1316) translated and added a supplement to the work of al-Maridini under the title De Veneris. Al-Muwaffaq’s contributions in the field are also pioneering. Living in the 10th century, he wrote The foundations of the true properties of Remedies, amongst others describing arsenious oxide, and being acquainted with silicic acid. He made clear distinction between sodium carbonate and potassium carbonate, and drew attention to the poisonous nature of copper compounds, especially copper vitriol, and also lead compounds. For the story, he also mentions the distillation of sea-water for drinking.
Abu al-Qasim al-Zahrawi (Abulcasis), regarded as the father of modern surgery, contributed greatly to the discipline of medical surgery with his Kitab al-Tasrif (Book of Concessions or The Method of Medicine), a 30-volume medical encyclopedia published in 1000, which was later translated to Latin and used in European medical schools for centuries. His influential al-Tasrif introduced his famous collection of over 200 surgical instruments. Many of these instruments were never used before by any previous surgeons. Hamidan, for example, listed at least twenty six innovative surgical instruments that Abulcasis introduced. The surgical instruments he invented include the first instruments unique to women, as well as the surgical uses of catgut and forceps, the ligature, surgical needle, scalpel, curette, retractor, surgical spoon, sound, surgical hook, surgical rod, and specula, bone saw, and plaster.
Ibn al-Haytham (Alhacen) made important advances in eye surgery, as he studied and correctly explained the process of sight and visual perception for the first time in his Book of Optics, published in 1021. Ammar ibn Ali al-Mawsili is also notable for inventing the injection syringe.
Other medical innovations first introduced by Muslim physicians include the discovery of the immune system, the introduction of microbiology, the use of animal testing, and the combination of medicine with other sciences (including agriculture, botany, chemistry, and pharmacology), as well as the first drugstores in Baghdad (754), the distinction between medicine and pharmacy in the 12th century, and the discovery of at least 2,000 medicinal substances. Other medical advances came in the fields of pharmacology and pharmacy.
Mental health and mental illness
Islam stressed the need for individual understanding of their mental health. Those afflicted with a mental illness were thought to be possessed by jinn (genies), supernatural spirits that can be either good or bad. The Qur'an mentions the idea of the spirit or soul constantly, preaching the idea that only though radical change of one’s conception of the universe can one move closer to God. Unlike the Jewish conception of mental illness as sin, the Islamic viewpoint interpreted mental illness as a sign of supernatural intervention that was not necessarily malignant. Changes in the psyche could be either good or bad – the Sufi movement of Islam, for instance, teaches spirituality though near-mysticism, using song, dance, and narcotics to induce an altered mental state and a closer connection of God. This new attitude towards the mind, freeing mental illness from implications of wrongdoing, paved the way for a more scientific examination of the causes and symptoms of mental illness. The first such advances were made by Islamic scholars.
The Persian physician Razi (Rhazes) wrote the landmark texts El-Mansuri and Al-Hawi in the 10th century, which presented definitions, symptoms, and treatments for many illness related to mental health and mental illness. He also ran the psychiatric ward of a Baghdad hospital. Such institutions could not exist in Europe at the time because of fear of demonic possessions. In the centuries to come, Islam would eventually serve as a critical waystation of knowledge for Renaissance Europe, through the Latin translations of many scientific Islamic texts.
Psychotherapy and psychiatry
In psychology, the Persian physician Razi (Rhazes) was the first to study psychotherapy and made significant advances in psychiatry in his landmark texts El-Mansuri and Al-Hawi in the 10th century, which presented definitions, symptoms, and treatments for problems related to mental health and mental illness. He also ran the psychiatric ward of a Baghdad hospital. Such institutions could not exist in Europe at the time because of fear of demonic possessions.
Ibn Sina was a pioneer of neuropsychiatry. He first described numerous neuropsychiatric conditions, including hallucination, insomnia, mania, nightmare, melancholia, dementia, epilepsy, paralysis, stroke, vertigo and tremor.
Experimental psychology and psychophysics
Ibn al-Haytham is considered by some to be the founder of experimental psychology and psychophysics, for his pioneering work on the psychology of visual perception in the Book of Optics. In Book III of the Book of Optics, Ibn al-Haytham was the first scientist to argue that vision occurs in the brain, rather than the eyes. He pointed out that personal experience has an affect on what people see and how they see, and that vision and perception are subjective. He explained possible errors in vision in detail, and as an example, describes how a small child with less experience may have more difficulty interpreting what he/she sees. He also gives an example of an adult that can make mistakes in vision because of how one's experience suggests that he/she is seeing one thing, when he/she is really seeing something else.
One author has argued that al-Haytham is also the founder of psychophysics, a distinct subdiscipline of psychology. This is a minority opinion and is based on a misunderstanding of the term. Psychophysics is a battery of quantitative statistical and mathmatical methods of relating changes in physical stimulus magnitude to perception. Although al-Haytham made many subjective reports regarding vision, there is no evidence that he used quantitative psychophysical techniques.
"Not only is every sensation attended by a corresponding change localized in the sense-organ, which demands a certain time, but also, between the stimulation of the organ and consciousness of the perception an interval of time must elapse, corresponding to the transmission of stimulus for some distance along the nerves."
Modern anesthesia was developed by Muslim anesthesiologists. They were the first to utilize oral as well as inhalant anesthetics. In Islamic Spain, Abu al-Qasim and Ibn Zuhr, among other Muslim surgeons, performed hundreds of surgeries under inhalant anesthesia with the use of narcotic-soaked sponges which were placed over the face. Muslim physicians also introduced the anesthetic value of opium derivatives during the Middle Ages. Ibn Sina (Avicenna) wrote about its medical uses in his works, which later incluenced the works of Paracelsus.
Razi (10th century) used mercurial compounds as topical antiseptics. From the 10th century, Muslim physicians and surgeons were applying purified alcohol to wounds as an antiseptic agent. Surgeons in Islamic Spain utilized special methods for maintaining antisepsis prior to and during surgery. They also originated specific protocols for maintaining hygiene during the post-operative period. Their success rate was so high that dignitaries throughout Europe came to Córdoba, Spain, to be treated at what was comparably the "Mayo Clinic" of the Middle Ages.
Medical and therapeutic drugs
Razi, Avicenna, al-Kindi, Ibn Rushd, Abu al-Qasim, Ibn Zuhr, Ibn Baytar, Ibn al-Jazzar, Ibn Juljul, Ibn al-Quff, Ibn an-Nafs, al-Biruni, Ibn Sahl and hundreds of other Muslim physicians developed drug therapy and medicinal drugs for the treatment of specific symptoms and diseases. The word "drug" is derived from Arabic. Their use of practical experience and careful observation was extensive.
Chemotherapeutical drugs were first developed in the Muslim world. Muslim physicians used a variety of specific substances to destroy microbes. They applied sulfur topically specifically to kill the scabies mite.
Numerous Muslim chemists produced medicinal-grade alcohol through distillation as early as the 10th century and manufactured on a large scale the first distillation devices for use in chemistry. They used alcohol as a solvent and antiseptic.
The medical procedure of inoculation was practiced in the medieval Islamic world, and was later followed by the first smallpox vaccine in the form of cowpox, invented in Turkey in the early 18th century.
Other surgical instruments invented by Abu al-Qasim and first described in his Al-Tasrif (1000) include the scalpel, curette, retractor, surgical spoon, sound, surgical hook, surgical rod, and specula, as well as the bone saw.
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