# The Contributions of Islamic Scholars

The Islamic Empire consisted of a society that was multicultural in terms of languages, customs, traditions and religion. As Muslims went forth from Arabia to conquer the countries surrounding them, they encompassed vast lands with peoples of different faiths and cultures. Thus the Islamic Empire not only consisted of Muslims from three continents, Arabs, Persians, Turks, Africans, Indians and other Asians, but also Jews, Christians and other faiths. Therefore scholars from all faiths worked under the umbrella of Islam to produce a unique culture of knowledge and learning. In the paragraphs that follow each major known field of science is considered and examined for the contributions made by scholars from the Islamic world.

## Medicine

Muslims gained access to the Greek medical knowledge of Hippocrates, Dioscorides, and Galen through the translations of their works in the seventh and eighth centuries. These initiatives by Muslims could be seen in the different aspects of the healing arts that were developed. The translation movement of the twelfth century in Latin Europe affected every known field of science, none more so than medicine (Meyers, 1964).

Two Muslim physicians who become known in Europe during this period were Ibn Sina (980-1037) and Al-Razi (865-925). Ibn Sina devoted his life to the study of medicine, philosophy and other branches of science. Renowned throughout medieval Europe as Avicenna, he established free hospitals and developed treatments for diseases using herbs, hot baths, and even major surgery. His famous book The Canon of Medicine was translated into Latin in the twelfth century and it was used in medical schools throughout Europe until the advent of modern science (Beshore, 1998; Meyers, 1964). The Canon of Medicine contained all Greek medical knowledge together with Arabic interpretations and contributions.

Ibn-Sina wrote some 99 books dealing with philosophy, medicine, geometry, astronomy, theology, philosophy, and art. Ibn-Sina was also known for Kitab al Shifa (Book of Healing), in which he divided practical knowledge into ethics, economics, and politics, and theoretical knowledge into mathematics, physics, and metaphysics (Meyers, 1964).

Al-Razi, known in Latin as Rhazes, excelled in the powers of observations and wrote some 184 works on topics that he studied as a practising doctor. One of Al-Razi’s books, Treatise on Smallpox and Measles, was translated into Latin, then English and other European languages, and “went through forty editions between the fifteenth and nineteenth century” (Turner, 1995, p.135). Furthermore, he established separate wards in hospitals for the mentally ill, thereby creating the means for clinical observations of these diseases. Al-Razi also included in his studies ideas involving human behaviour and he was a pioneer in the field of psychology, thus removing the theories of demons and witchcraft associated with these diseases in the Christian world.

By the twelfth century Muslim physicians had produced many works: encyclopaedias, medical biographies, texts on medical ethics, and on specialist topics such as ophthalmology. Ibn An-Nafīs contradicted the

theories of blood circulation as put forward by Galen. He advanced a theory of blood circulation between the compartments of the heart and the lungs, and of pulmonary circulation or lesser circulation. In 1553, three centuries later, a Spaniard Miguel Serveto (Michael Servetus) forwarded a similar theory (Meyerhof, 1935). Ibn An-Nafīs’s theory from the thirteenth century was largely ignored. But he was among the initial precursors to Harvey’s scholarly work that revealed the circulation of blood in the human body.

Muslims using their clinical and surgical knowledge established hospitals. These institutions were far superior to any that existed in ancient times or in lands beyond the Islamic Empire. In medieval Europe most hospitals were attached to religious orders and monasteries. In the Islamic world, during the eighth century the first hospital was built in Damascus; having separate wards for males and females, and special wards for internal diseases, surgery, orthopaedics and other diseases. These hospitals were to become models for hospitals as we know them today (Turner, 1995).

Important surgical treatises were written in the tenth and the eleventh centuries in Andalusia by Abu’l-Qasim al-Zahrawi, known in Europe as Abulcais. His book Kitab al-Tasrif (Book of Concessions), a medical almanac, was translated into Latin and used by Muslims and in European medical schools. The twelfth century physician in Muslim Spain, Ibn Zuhr, known as Avenzoar, wrote works especially in anatomy that had a great influence on medical practice in medieval Europe. Thus in the medical field scholars from the Islamic world had much to contribute both in terms of working with ancient knowledge and through the major developments of their own. Moreover, they verified their theories through careful observations in the hospitals that they had established.

## Chemistry, Pharmacology and Pharmacy

In chemistry, the works of Jaber ibn Haiyan and Al-Razi formed the basis of modern science. Jaber, know as Geber in Latin, described in his works the preparation of many chemical substances: the sulphide of mercury, oxides and arsenic compounds. Al-Razi in his book Secret of Secrets know as Liber secretorum bubacaris, described the chemical processes and experiments he conducted. Hill (1993, p.83) has stated that Al-Razi’s book Secret of Secrets ‘foreshadows a laboratory manual’ it deals with substances, equipment and procedures. Muslim chemists developed recipes for products that had industrial and military applications. The discovery of inorganic acids during chemical experiments had valuable industrial applications in the centuries that followed.

In the fields of pharmacology and pharmacy Muslims made notable progress. These fields involved scientific investigation into the composition, dosages, uses and therapeutic effects of drugs. Having translations of Dioscorides’ De Materis Medica, along with knowledge from Syria, Persia, India and the Far East, Muslim scholars and physicians showed great innovative skills. They developed the procedures for the manufacture of syrups and juleps, and established apothecary shops (Turner, 1995). Ibn al-Baytar’s book Al-Jami‘fi al-Tibb (Collection of Simple Diets and Drugs) contained detailed records of the plants in the lands along the length of the Mediterranean coast between Spain and Syria. In addition, he systematically

compared this knowledge with that of the scientists of previous eras. His book on botany was used until the Renaissance by Europeans.

## Mathematical Sciences

The mathematical sciences as practised in the Islamic world during this period consisted of mathematics, algebra, and geometry as well as mathematical geography, astronomy and optics. Muslims derived their theory of numbers (‘ilm al-a‘dad) in arithmetic from translations of the Greeks sources such as Books VΙΙ through to ΙX of Euclid’s Elements and the Introduction to the Science of Numbers by Nicomachus of Gerasa (Berggren, 1997). Moreover, they acquired numerals from India (Hindu) and possibly China and made their use widespread. Mohammad Bin Ahmed in the tenth century invented the concept of zero or sifr. Thus replacing the cumbersome Roman numerals and creating a revolution in mathematics (Badawi, 2002). This led to advances in the prediction of the movement of the planets and advances in the fields of astronomy and geography.

Muslim mathematics had inherited both the Babylonian sexagecimal system and the Indian (Hindu) decimal system, and this provided the basis for numerical techniques in mathematic (Folkerts, 2001; Rajagopal, 1993). Muslims built mathematical models using the decimal system, expressing all numbers by means of ten symbols, and each symbol accorded the value of position as well as absolute value (Kettani, 1976). Many creative methods of doing multiplications were developed by Muslims; methods of checking by casting out nines, and decimal fractions (Anawati, 1976). Thus Muslim scholars contributed and laid the foundations of modern mathematics and the use of mathematics in the fields of science and engineering (Høyrup, 1987).

Thabit bin Qurrah not only translated Greek works but also argued against and elaborated on the widely accepted views of Aristotle. In arithmetic there emerged the concept of irrational numbers with Islamic mathematicians starting from a non-Euclidean concept. Both Umar Khayyam (1048-1131) and Nasir al-Din al-Tusi (1201-1274) contributed to research on this concept which did not have its origins in Greek mathematics.

Eastern Muslims derived numerals from Sanskrit-١‘٢‘٣‘٤‘٥‘٦‘٧‘٨ and ٩, and they were the first to develop the use of the zero (sifr), written as 0 by the Western Muslims and ‘·’ by Eastern Muslims (Kettani, 1976, p.137). Whereas these Eastern Muslims had initially used the Arabic alphabets as numerals, by the ninth century Western Muslims had invented and replaced them with “al-arqam al-gubariyah-1,2,3,4,5,6,7,8 and 9-based on a number of angles equal to the weight of each symbol” (Kettani,1976, p.137). Thus the zero with the numerals made it possible for the simple expressions for numbers to have infinite values, thereby helping solve particular problems. Translations of mathematical treatise in Spain subsequently transferred this knowledge to Europe.

Al-Khwarizmi wrote the first book of algebra, the word ‘algebra’ transliterates into the term al-jabr. Al-jabr represents the two basic

operations used by al-Khwarizmi in solving quadratic equations. In the latter half of the twelfth century, the first part of al-Khwarizmi’s Kitab al-Jabr wa al-Muqabalah was translated and made available in Europe (Kettani, 1976; Sarton, 1927). Another famous contributor to this field was Umar Khayyam, who studied cubic equations and algebra came to be regarded as a science in its own right. Subsequently in later centuries Italians took over his methods and extended them (Anawati, 1976). Thus the Muslims not only developed the methods of solving quadratic equations they also produced tables containing sine, cosine, co-tangent and other trigonometrical values. Al-Battani (d.929) systematically developed trigonometry and extended it to spherical trigonometry (Kettani, 1976; Sarton, 1927), with important consequences for astronomy, geography and exploration beyond the known world, thus making the construction of better maps and the reconceptualisation of the structure of the planet Earth.

Arabic geometry absorbed not only materials and methods of Euclid’s Elements but also the works of Apollonius and Archimedes. The book, On the Measurements of Planes and Spherical Figures, written on Archimedean problems by the three sons of Musa bin Shakir in the ninth century became known in the West through the translation by Gerard of Cremona. In seventeenth century Europe the problems formulated by Ibn al-Haytham (965-1041) became known as “Alhazen’s problem”. Again his work that was translated into Latin made Europeans aware of al-Haytham’s remarkable achievements in the field of Optics (Kitab al-Manazir) (Meyers, 1964, p.32). Among his works were included a theory of vision and a theory of light, and was called by his successors of the twelfth century “Ptolemy the Second”. Furthermore by promoting the use of experiments in scientific research, al-Haytham played an important role in setting the scene in modern science (Rashed, 2002, p.773).

Al-Haytham’s contributions to geometry and number theory went well beyond the Archimedean tradition. Al-Haytham also worked on analytical geometry and the beginnings of the link between algebra and geometry. Subsequently, this work led in pure mathematics to the harmonious fusion of algebra and geometry that was epitomised by Descartes in geometric analysis and by Newton in the calculus. Al-Haytham was a scientist who made major contributions to the fields of mathematics, physics and astronomy during the latter half of the tenth century. John Peckham in the late-thirteenth century used al-Haytham’s Kitab al-Manazir and Witelo’s Optics too has echoes of Kitab al-Manazir. Witelo work was used by Johannes Kepler. Roger Bacon, the founder of experimental science, probably used the original Arabic works of al-Haytham as well as Latin translations (Meyers, 1964).

Much work was under-taken by Islamic mathematicians regarding the theory of parallels. This theory consisted of a group of theorems whose proofs depended on Euclidean postulates. The Islamic mathematicians continued their research for over 500 years on these postulates in order to obtain proofs and not just the acceptance of them. However, after these problems were transmitted to Europe in the twelfth century, little further research was done until the sixteenth century. Muslim scholars contributed

not only to the use of logic in the development of mathematical ideas and relationships, but also to a workable system of numeration that included zero and led to the solution of equations. Muslims had thus begun the work that led on to mathematical modelling and its application for the purpose of testing their theories. This knowledge and approach was slowly transferred to Europe through Spain and Sicily.

## Astronomy

Muslim scholars considered astronomy as one of the mathematical sciences. Muslims came across ancient astronomical manuscripts and translated them into Arabic. They then undertook observations to verify the calculations in these scientific works. The Greek astronomer Ptolemy had developed an astronomical theory about the movements of the moon and planets; and had placed the earth at the centre of the universe. In order to compensate for errors in observation he had attributed additional movements to the planets. Al-Khwarizmi was one of the first scholars to produce a detailed astronomical table (zij). This astronomical table provided the means of calculating the positions of the stars and planets. Subsequently, each astronomer wrote his own zij, trying to make it more accurate than those prepared before (Beshore, 1998). Al-Farghani, in the ninth century wrote a detailed account of Ptolemy’s Almagest and his book was used throughout Europe and central Asia for the next 700 years (Beshore, 1998, p. 24). This work was the beginnings of the empirical verification of scientific ideas and relationships.

Muslim philosophers and astronomers had inherited the Ptolemaic planetary system that hypothesised the principle of uniform circular motion allowing the planets to move in epicycles. However, Muslim astronomers eventually came to reject this theory in that the epicyclic movement violated the principle of uniformity of motion. In the thirteenth century, Al-Tusi, a Persian astronomer put forward his concept known as the “Tusi Couple”, a hypothetical model of “epicyclic motion that involves a combination of motions each of which was uniform with respect to its own center”(Turner, 1995, p.68). This model was applied by Ibn al-Shatir to the motions of the heavenly bodies in the fourteenth century. Ibn al-Shatir’s formulations were the beginnings of verifying theoretical astronomy through systematic observations.

Ibn al-Shatir’s theory of lunar motion was very similar to that attributed to Copernicus some 150 years later (Sabra, 2002). Currently researchers are investigating whether it was possible, that Copernicus visiting the Vatican library in Rome had seen Ibn al-Shatir’s fourteenth century manuscript illustrating his concept of planetary motion (Saliba, 2002). The reason for this supposition being a diagram in Copernicus’ Commentaries that was remarkable similar to Ibn al-Shatir’s schematic diagrams. Whereas Ibn al-Shatir’s concept of planetary motion was conceived in order to play an important role in an earth-centred planetary model, Copernicus used the same concept of motion to present his sun-centred planetary model. Thus the development of alternative models took place that permitted an empirical testing of the models.

Whether there was a clearly identifiable connection between the works of these two men today remains unclear, but what needs to be noted is that Muslim innovations in astronomical theory contributed to the historical development of astronomical science (Turner, 1995). These innovations provided new directions for investigations during the ages of the Renaissance and Enlightenment in Europe. Another development that was attributed to al-Tusi, the thirteenth century astronomer, was that he treated trigonometry as a separate field from spherical astronomy. Thus astronomers could calculate distances and directions of points on the celestial spheres more efficiently, using this new body of mathematical ideas and relationships.

Muslims also built large observatories in Maragha and Samarkand, and later at Delhi and Jaipur, and in Turkey. They improved on the Greek sundial and astrolabe, adding features by means of which they could calculate the timings of Muslim prayers and the direction to Mecca. The medieval astrolabe could be calibrated for use at different geographical locations to calculate year-long celestial time keeping data, and other astronomical information (Turner, 1995). These medieval astrolabes reached Europe in the late Middle Ages and were mentioned in many texts, and were included in an essay by Geoffrey Chaucer. Celestial globes, astrolabes, quadrants, and sundials all evolved and developed in Islamic countries, and when the compass arrived in the Islamic lands, it too was adapted by the Muslims. However they may not have initiated the use of the compass, because it would seem the origins of the use of the compass have not clearly been identified, and may have originated in China.

Thus Muslim scholars worked in all major branches of astronomy: theoretical and computational planetary astronomy, spherical astronomy and time keeping, instrumentation, and folk astronomy. King (2004) did extensive research on Muslim instrumentation and stated that “medieval European instrumentation was highly indebted to the Islamic tradition, and now it is clear only after ca.1550 did European instrument-makers make technical innovations that had not been known to Muslim astronomers previously” (King, 2004, p.47).