Abu Rayhan al-Biruni, also known simply as al-Biruni, was undoubtedly one of the greatest polymaths of the Islamic Golden Age. Among his many areas of study, al-Biruni stands out mainly in mathematics, physics, astronomy, science and also history, chronology and linguistics, being versed in each one of them. Going further, al-Biruni is usually called the father of comparative religion studies, as well as the father of indology1, modern geodesy2 and the first anthropologist.

Born in Kath3 in 973, until then capital of the Afrighid Dynasty of Khwarezm, al-Biruni lived during a period of heyday in the sciences within the Islamic world, also known as the Golden Age, a time when scientific research and scholarship were largely financed by the caliphs of the Abbasid caliphate.

Despite having achieved a certain proficiency in the various areas of knowledge, al-Biruni during the first 25 years of his life also studied grammar, theology, Islamic jurisprudence (fiqh), medicine and other sciences.

Coming from a highly cultured society and known for its mathematical, scientific, astronomical tradition, etc., al-Biruni studied with no less than a prince, Abu Nasr Mansur, who was also a great mathematician.

Al-Biruni served as secretary to the prince and was responsible for sending copies of his works to other important scientific figures, such as the mathematician and astronomer Abu l-Wafa al-Buzjani (940-998). However, such a situation would not last for long. A civil war broke out in the region that ended with the triumph of the Mamuni dynasty and the death of the monarch Abu Abd Allah Muhammad b. Ahmad in 995.

Although it is not possible to know all the dates of al-Biruni’s life, some we do know exactly because he documented them in his astronomical works, such as the lunar eclipse of May 24, 997 in which he observed in his hometown, Kath. Although we do not know how or why, we have the information that a-Biruni returned to his country of origin at some point.

Philosophy and Theology

Although philosophy and theology were not the main areas of study of al-Biruni, he still had some writings on these topics, refuting the legendary Avicenna (Ibn Sina) during some letter correspondences between the two sages.

In the writings, al-Biruni would refute Avicenna’s position regarding the Eternal Universe, thus defending Islamic orthodoxy, something that the great Imam al-Ghazali would a time later.

Al-Biruni, who was a Sunni Ashari (Islamic theological school) Muslim, would defend the position that the universe had a beginning, being created ex nihilo (out of nothing), claiming that Aristotle’s position on which Avicenna was based on was largely contradictory, because according to Biruni, the Greek sage stated that the universe and matter has a start whilst holding on to the idea that matter is pre-eternal. The nuances of al-Biruni’s argument against Ibn Sina go much further. Such a debate resulted in al-Biruni proud of himself, as he did not abandon the precepts of his religion in favor of the thoughts of the classical Greeks, as of Aristotle’s himself.

Chronology and Trigonometry

Written after 998, al-Athar al-baqiya (Chronology of Ancient Nations) is among al-Biruni’s early works. In this work he begins with an analysis of the day as a fundamental chronological unit and goes on to describe the solar, lunar and lunisolar years, as well as the different times used by various cultures and the names of the months, before concluding with a detailed description of the Jewish calendar.

With regard to trigonometry, Al-Biruni’s Maqalid ilm al-haya (The Keys of Astronomy) was the first known treatise on spherical trigonometry, which also dates from this early period near 998, shortly after observing the lunar eclipse in his hometown.

At the turn of the 11th century, Abu Nasr Mansur (the prince teacher of al-Biruni), Abu l-Wafa al-Buzjani and Abu Mahmud al-Khujandi developed theorems that became the laws of sines, cosines and tangents. These new theorems had an obvious advantage. They establish relationships between the sides and angles of a single triangle. The role of the Maqalid work by al-Biruni was precisely to systematize this new trigonometry, which reached the Islamic West (that is, al-Andalus) and was systematized again by Ibn Muadh of Jaen (m. 1093), and later by Jabir ibn Aflah of Seville during the first half of the 12th century.

Another important contribution devoted to al-Biruni’s trigonometry was his work Kitab fi ifrad al-maqal fi amr al-zilal (The Exhaustive Treaty on Shadows). Al-Biruni was one of the first mathematicians to calculate tangent and cotangent tables, as well as sines and cosines.

Indology

Considered as the father of indology, al-Biruni’s works on the country are extremely comprehensive, covering subjects such as geography, geology, science, history, religion, aspects of the daily life of Indians and so on, as is the case with his work Tahqiq ma li-l-Hind min maqulah maqbulah fi al-aql aw mardhulah, also translated as “The book confirming everything what pertains to India, whether rational or despicable”.

Al-Biruni studied the Hindu religion deeply, even translating the famous works of the sage Patanjali, author of numerous works in Sanskrit. Something that draws attention in the works of al-Biruni is his objectivity towards Hinduism and its faithful, stating:

I shall not produce the arguments of our antagonists in order to refute such of them, as I believe to be in the wrong. My book is nothing but a simple historic record of facts. I shall place before the reader the theories of the Hindus exactly as they are, and I shall mention in connection with them similar theories of the Greeks in order to show the relationship existing between them.

In this way, al-Biruni also sought to understand the significant hatred that the faithful of Hinduism harbored for Muslims, who were considered impure and violent. Thus, Biruni found that the invasions of Muslims in the 11th century in India resulted in this perception on the part of Hindu natives in the country, which contributed to the fact that Hindus were increasingly suspicious of all foreigners who set foot in Indian territory, not just Muslims.

Despite this, al-Biruni managed to gain the confidence of many Hindu sages, even studying with them to achieve fluency in Sanskrit, so that he could translate works of mathematics, science, medicine, astronomy and other areas of knowledge into Arabic. Not only, but al-Biruni was also inspired by the arguments offered by Indian scholars about the sphericity of the Earth, which for them would be the only way to explain the hours of the day by latitude, seasons and relative positions of the Earth with the moon and the stars.

Although al-Biruni was extremely objective in his reports, he nevertheless criticized the Hindus in other writings, such as the Indians’ lack of curiosity about their religion and history. In addition, he did not focus on “boring” issues like governments and battles, but on the daily lives of Indians, their culture and tradition, and their reports and descriptions of the geography of India in their time and also of its natural aspects they are used today by historians to locate certain regions in modern India.

Anthropology

As can be seen in Biruni’s travels and stay in India, he wrote about the Indian people, their customs, traditions, religiosity, their daily lives and even about the geography of their nation. Thus, always with the maximum neutrality and objectivity possible, al-Biruni participated in an extensive observation about Hindus, even going to live with them and learning their customs in practice, as well as their language and their primary texts directly from the wise men of his time.

For Akhbar Ahmed (1984), al-Biruni can be considered the first anthropologist in history, although this statement is not absolute, receiving objections.

History of Religions and Comparative Religion

Despite his deep study in Hinduism, this was not the only religion studied by al-Biruni, who also had contact with Christianity, Judaism, Buddhism and Zoroastrianism.

Even though Biruni recognized Islam as being a superior religion to the others, this has not yet prevented him from having an objective study on the belief of other religious traditions, unlike many writers of his time and even today, who instead of studying a subject seriously and understand it first, go straight to the attempts of “refutation”.

Expressing admiration for other creeds, al-Biruni often quoted texts from other religions in his conclusions, seeking to understand them instead of proving that they were wrong and that Islam was correct, despite his personal convictions.

Geodesy and Geography

Regarding Geography, al-Biruni has several writings during the time he traveled through India with Mahmud of Ghazni in his raids. However, a curious fact is that al-Biruni in his work known in the West as Codex Masudicus of 1037 theorized that there was a huge landmass in the vast ocean between Europe and Asia, arguing based on the circumference of the Earth and his other studies of geodesy. This broad mass of land theorized by Biruni would be what we know today as America, despite the fact that he was not aware of it, but rather an estimative based on the circumference of the planet, arguing further that at least some of these lands could be inhabited, and that in fact one day they would be.

In his geodesy studies, al-Biruni even used his aforementioned studies in trigonometry to calculate the Earth’s radius, being only 2% higher than modern estimatives. His method of evaluating the Earth’s radius was innovative, since it determined it by observing the height of the mountains, observing the Pakistani mountains in the region of Punjab, an Indian state bordering Pakistan.

Al-Biruni would die in 1050 at the age of 77, and despite having incredible and innovative works, he would remained unnoticed until his studies on indology came to be used by western countries, mainly by the British Empire in their activities in India in the 17th century.

Notes:

[1] Indology is the academic study of the Indian subcontinent, covering history, culture, literature and other studies related to Asia.

[2] Area that studies the planet Earth, its geometric shape, orientation in space and gravitational field. Aristotle was the first to study such this area, but the title “the father of modern geodesy” belongs to al-Biruni.

[3] Nowadays the city where al-Biruni was born takes his name, Biruni, in honor of the great Muslim polymath.

BIBLIOGRAPHY

SAMSÓ, Julio. Al-Biruni. The First Golden Age of Islamic Science. Inference. 2018.

BOSWORTH, C.E. BĪRŪNĪ, ABŪ RAYḤĀN. Iranica Online. 2010.

KENNEDY,  E S Kennedy. Biography in Dictionary of Scientific Biography. 1970.

GLICK, Thomas F.; LIVESEY, Steven John; WALLIS, Faith. Medieval Science, Technology, and Medicine: An Encyclopedia. 2005

AHMED, Akbar S. (1984). Al-Beruni: The First Anthropologist. Jstor. 1984