For more than 60 years, Fuat Sezgin searched libraries around the world, creating a comprehensive bibliography of almost every known text on Muslim-Arabic sciences, much of which has been borrowed yet overlooked by the West.

One of the most prolific historians of Islamic science of our time, he visited libraries around the world to study nearly every aspect of Arabic literature and, in the process, collected thousands of books, some of them rare manuscripts.

Diophantus, the famous Greek mathematician, has long been a mystery to researchers. Little is known about his life, and there is still debate over whether he lived in 150 B.C. or A.D. 364. What is known for sure is that he wrote the magnum opus Arithmetica, a book that for centuries was essential reading for anyone interested in number theory and algebra. However, seven of the book's 13 chapters were thought to have been lost in the upheavals of the Middle Ages, when Muslims and Christians fought bloody battles. In 1968, Sezgin made an interesting discovery while studying old manuscripts in the Astan Quds Library in Mashhad, Iran.

Tucked among bundles of decaying papers was an Arabic translation of Diophantus' book written by Qusta ibn Luqqa, a Christian polymath who flourished in ninth-century Baghdad, then the center of the Islamic empire. It was a monumental find that provided valuable insight into the work of Diophantus.

"The part (Sezgin found) shows us that the work of Diophantus was indeed a book from which ancient students could learn algebraic methods of solving problems," Jacques Sesiano, who wrote a thesis on the discovered chapters in 1975, told TRT World. "And this may explain why no work of Diophantus' predecessors has survived."

Sezgin explored libraries in Türkiye, Iran, Egypt, India and many other countries, immersing himself in papers written by little-known authors. In the process, he compiled what is today regarded as the most comprehensive bibliography of Arabic literature, covering subjects ranging from Qur'anic sciences, religious doctrine, zoology and alchemy to astronomy and astrology. His achievements in the history of science are numerous, ranging from his research on the cartographer Piri Reis to supervising the construction of astrolabes based on 10th-century designs. Many of his contemporaries were not even aware of the discovery of the Diophantus manuscripts.

"If you hear of any writer, book or ancient work written in Arabic, and you want to find out anything about it, the first thing you do is go to Fuat Sezgin's book," says Peter Starr, a professor of Islamic history at the Fuat Sezgin Institute in Istanbul.

For Sezgin, his lifelong endeavor to piece together the history of Islamic science began with a chance meeting.

The expulsion

In 1943, Hellmut Ritter, a German professor of Arabic literature, was delivering a lecture at Istanbul University's Institute of Oriental Studies. Among the audience was 19-year-old Sezgin, who had come to the city from his hometown of Bitlis in eastern Türkiye with hopes of becoming a mathematician. After attending Ritter's lecture, Sezgin changed his mind.

Sezgin was born in 1924, a year after the Ottomans were driven out of Istanbul and Mustafa Kemal Atatürk had declared Türkiye a republic.

"Meeting Ritter was a life-changing experience for him," says Musa Serdar Çelebi, who had known Sezgin since the 1980s. "Ritter was very demanding. He made Sezgin study the works of Muhammad ibn Jarir al-Tabari and al-Ghazali. He made his young disciple study more than 15 hours a day."

Ritter had lived in Istanbul for many years. The city's ancient libraries contained a treasure trove of manuscripts that had not been properly studied. He was among the few European scholars who subscribed to the view that Muslim scientists had not been given their due place in history. That thinking had a profound impact on Sezgin, who would eventually become a lifelong admirer of the German Orientalist tradition, which encouraged deep scholarly research.

"It was like a big, big puzzle for him. You know, like an archaeologist who's onto something and then he gets really excited about it and wants to find it all," Hilal Sezgin, his daughter, a journalist and well-known author in her own right, told TRT World.

Sezgin's career was almost cut short on May 27, 1960, when the Turkish military overthrew the government of the Democratic Party. Civil servants, doctors and teachers were fired overnight for even slight connections to political parties. Sezgin also lost his job because of his brother's ties to a political party. The experience left him disillusioned with his country.

Later, he would often remark that one of the most fortunate things to happen to him was "my expulsion." He followed his mentor Ritter to Germany and joined Frankfurt University.

By the 1970s, Sezgin was regarded as an authority in his field, with his findings and research regularly featured in leading academic journals.

Gerald J. Toomer, a professor of history at Brown University, wrote in the 1980s: "The great increase during the last 20 years in our information about the manuscript materials in all areas of Arabic studies is due principally to the work of Fuat Sezgin."

What Renaissance?

Sezgin did not take long to realize that many European and American scholars had ignored the contributions of Islamic science to world civilization. For them, the world had plunged into intellectual darkness for more than a thousand years following the decline of the Roman Empire in the fifth century.

With the spread of Islam in the seventh century, centers of learning, laboratories and schools emerged in Baghdad, Tehran and elsewhere. Muslim scholars continuously studied, experimented and developed new tools and ideas that contributed to humanity's progress.

"What he said often was that there's no such thing as the Renaissance," says Starr. "The word Renaissance means rebirth, which implies that Europeans were trying to bring back the science of the classical Greeks. But science never died. Arabs inherited the finest achievements of Greek science, built upon them and passed them on."

A replica of a 10th-century astrolabe that Sezgin helped design is among dozens of instruments on display at the Istanbul Museum of the History of Science and Technology in Islam.

A great deal of Sezgin's work focused on one of the most flourishing periods in Muslim history. In the ninth century, al-Ma'mun of the Abbasid dynasty ruled the Islamic world from Baghdad. Under his leadership, the city became a center of learning where Muslims, Christians and Jews studied various disciplines. It also ushered in a major translation movement, during which the works of Plato, Aristotle, Ptolemy, Euclid and other Greek thinkers were translated into Arabic.

Muslim scholars gradually expanded upon the knowledge inherited from ancient civilizations, leaving a lasting impact on future generations. Jabir ibn Hayyan, the pioneering alchemist, introduced the term "alkali" into scientific vocabulary. Muhammad ibn Musa al-Khwarizmi wrote the influential work Kitab al-Jabr, ensuring that the word "algebra" would forever be associated with his name.

That era also saw Muslim explorers venturing across seas, measuring distances, discovering routes to Africa and Asia, and producing increasingly sophisticated maps. Yet European figures are often credited with much of this cartographic work, while the contributions of their Muslim predecessors are frequently overlooked.

Sezgin spent considerable effort piecing together the map commissioned by Caliph al-Ma'mun.

In the early 1980s, Sezgin found a copy of a map that al-Ma'mun had commissioned geographers to draw. Besides providing a more accurate representation of the Earth, the map corrected a mistake made centuries earlier by Ptolemy: it showed that the Indian Ocean and the Atlantic Ocean were not merely inland seas.

"Sezgin's important contribution was that it demonstrated the role of Muslims in geography and cartography. He basically overcame the Renaissance model, which marginalized 800 years of Muslim contributions," says Dr. Detlev Quintern, a history professor at the Fuat Sezgin Foundation.

Another subject that occupied Sezgin for many years was the reconstruction of models of Muslim inventions. At Frankfurt University, he spent years overseeing the design and construction of astrolabes, water-pumping systems and laboratory instruments once used by Muslim engineers and surgeons. These instruments remain on display in a museum at the university.

Much of this work was supervised by Ayman Naffai, an Egyptian civil engineer who began building instruments for Sezgin in 1991.

"He was very demanding and thorough in what he wanted. We made machines using everything—wood, silver, gold and copper. And we succeeded in producing exact replicas."

It was al-Ma'mun's map, recreated in the form of a globe, that proved to be the most challenging project.

"That's the globe at the entrance of the museum in Istanbul. It's all copper, handmade. It took us six months to build the structure and even longer to get the 3D map right," says Naffai.

What concerns him today is the lack of interest in Muslim scientific inventions.

"With Sezgin, this yearning to preserve our history might end forever. There's no one after him to continue this kind of work."

According to many of his colleagues and friends, Sezgin worked 15 hours a day for most of his adult life. For many years, and to some extent even today, he was known primarily within academic circles. This was largely because most of his books and papers were published only in German, and very little of his work was translated into English.

One exception is the five-volume catalogue of instruments displayed in the Frankfurt and Istanbul museums dedicated to the history of Arabic-Islamic science. In 2008, Professor Sreeramula Rajeswara Sarma, a historian of science specializing in ancient Indian languages, and his wife, Dr. Renate Sarma, published a translated version of Sezgin's catalogue.

"His books are not very well known because he published only a limited number of copies, perhaps in the hundreds. Also, most of his works are in German. But people who work in the field all know him," Sreeramula once told TRT World.

The two became friends in 1996, when Sreeramula first encountered the replicas of the scientific instruments Sezgin had commissioned.

Back in Türkiye

The Sezgin family visited Türkiye almost every year. His wife, Ursula, was also a historian. Although he spent most of his professional career in Germany, Sezgin's reputation gradually grew in his home country as his books and articles began to be translated into Turkish.

In the mid-2000s, Turkish officials approached him about establishing a research institute in Istanbul.

The reception Sezgin received in Türkiye was unprecedented for an academic. The government allocated space for a museum and a university within the grounds of Istanbul's historic Gülhane Park.

Over the years, Sezgin had built a personal library containing thousands of books, including rare manuscripts that he had discovered himself. When he attempted to transfer this collection to Istanbul, Frankfurt University filed a legal case against him. Authorities even prevented him from accessing his office.

The bitter experience, however, did not diminish Sezgin's admiration for German and European scholarship, something reflected in the Istanbul Museum of the History of Science and Technology in Islam. Visitors entering the museum first encounter a mural of Johann Wolfgang von Goethe, followed by figures such as Ernest Renan and Eduard Sachau.

Sezgin died in June 2018 at the age of 92. He was buried on the grounds of Topkapı Palace, an honor granted by the Turkish government. Senior officials, including President Recep Tayyip Erdoğan, attended his funeral.