Aydin Sayili (1913-1993) At Work: His Scientific Biography

Aydin Sayili is one of the first eminent figures of the history of science in Islam to pursue an academic career in this discipline. He was fortunate to earn the first PhD from the history of science chair established by George Sarton in Harvard University. With this distinguished background, he made valuable contributions to this field throughout his life. In the following article, Professor Ekmeleddin Ihsanoglu draws a lively picture of the scientific biography of the late Aydin Sayili (1913-1993) and points out the hallmarks of his scholarly work.

Ekmeleddin Ihsanoglu*

This article was first published in the well-known journal of history of science ‘Archives internationales d’histoire des sciences’ (vol. 45, no. 134, pp. 135-148.). We are grateful to Professor Ekmeleddin Ihsanoglu, the author of the article, for allowing publication.

Aydin Sayili is one of the first eminent figures of the history of science in Islam to pursue an academic career in this discipline. He was fortunate to earn the first PhD from the history of science chair established by George Sarton in Harvard University. With this distinguished background, he made valuable contributions to this field throughout his life.

Figure 1: The young Aydin Sayili. Courtesy of Dr. Hüseyin Gazi Topdemir.

Sayili was born in Istanbul in 1913. He spent a few years of his childhood in Iran, since his father Abdurrahman Sayili who later entered the teaching profession, was then a member of the Foreign Service. He completed his primary education in Istanbul and Ankara and his secondary education in Ankara where he graduated from Ankara Ataturk School (at that time called Ankara School for Boys) in 1933. During the final examinations, he took the Baccalaureate oral examination, which included the group of history, geography, and civics courses. Ataturk himself was present during this examination from the beginning until the end. Mr Avni (Yukariuc) was deputy director of the high school at that time. He told Aydin Sayili that the examination went on for one hour and twenty minutes. Ataturk was very pleased with his answers and told Resit Galip Bey, Minister of Education of the time, who was present at the exam, to give due attention to him. As a result of this interest, Sayili gave up his previous goals of becoming a hydraulic engineer or a physicist and decided to specialise in history of science, instead.

He entered the competitive state examinations and was sent to Harvard University, USA, by the Turkish Ministry of Education for his higher education. There, he studied with Professor Sarton who was a foremost pioneer in the field of history of science and one of the central figures in giving it the status of an independent academic discipline. Aydin Sayili training at Harvard was broad in scope. His so-called ‘horizontal’ specialisation or concentration in history of science was in the world of Islam and his ‘vertical’ specialisation in the history of physics. He also attended the summer training programs at Columbia and Cornell Universities. He earned his PhD degree in the history of science in 1942 from Harvard University which was apparently the first such degree to be granted in that discipline in Harvard University and in the world. (See Isis, 33 [1942], 714; 39 [1948], 240.)

Sayili returned to Turkey in 1943 and began his academic career in an auxiliary capacity at the Faculty of Letters (Dil ve Tarih-Cografya Fakültesi) of what became about three years later Ankara University. He became associate professor (docent) the same faculty in 1946. He was promoted to professorship in 1952 and to distinguished professorship – what was known in Turkish universities as ordinarius (misconception of German head of department) in 1958.

Figure 2: Aydin Sayili at the height of his academic career. Picture from: G. A. Russell, “Aydin Sayili: 1913-1993” (Isis, vol. 87, 1996, pp. 672-675).

An independent chair of the history of science was officially established in the Faculty of Letters of Ankara University in 1952. This is the first chair in history of science in Turkey and one of the earliest of the chairs of its kind in the world. Professor Sayili was its director from its establishment until he retired in 1983 when he reached the age limit. Beginning with the official foundation of the Department of Philosophy in the same faculty in 1974, he served as chairman of this department. It comprised six chairs. Sayili was elected to full membership of the Turkish Historical Society in 1947. He became corresponding member of the International Academy of the History of Science centred in Paris in 1957. He was made full member of the same academy in 1961 and was elected vice president for a period of three years in 1962. Professor Sayili was full member of the Society of Turkish Librarians. He was elected to honorary memberships of the same Society and of Deutsche Morgenländischen Gesellschaft in 1989. For several years, he served as the head of the section for the Middle Ages of the Turkish Historical Society. He received the ‘service award’ of the Turkish Society for Scientific and Technological Research in 1977 and ‘the certificate of merit award’ of Istanbul Technical University, Institute of History of Science and Technology in 1981. Sayili was the main speaker in the meeting organised in Ankara in 1973 by the Turkish Commission for the UNESCO to celebrate the five hundredth anniversary of Copernicus’ birth. He was presented, in 1973, with a Copernicus medal by the Polish ambassador in Ankara for his studies on Copernicus on the occasion of his 500th birth anniversary. He received the ‘Honorary Award of Service’ from Türkiye Ilim ve Edebiyat Eseri Sahipleri Meslek Birligi (ILESAM) on 15 May 1993.

Aydin Sayili was elected to membership of the International Editorial Committee for preparing a six-volume work on the history of Central Asian Civilisations for UNESCO’s Paris centre. In 1992 he was awarded by the Director General of UNESCO with Nehru medal for his work in this committee. Beginning with October 1983 he served as president of -the Atatürk Culture Centre of the Atatürk Higher Society for Culture, Language, and History which was established in the same year and published the periodical Erdem, a publication of this institution. He also continued to give post-graduate courses in the history of science in Ankara University.

Sayili participated in the following international congresses and scientific meetings: The international orientalists’ congress held in Istanbul in 1951; the international congresses of the history of science of the years 1953, 1956, 1959, 1962, and 1974 held respectively in Israel (Jerusalem and Tel Aviv), Italy (Florence), Spain (Barcelona and Madrid), the United States (Philadelphia and Ithaca) and Japan (Tokyo and Kyoto); Congress of the American History of Science Society held in New York City in 1956; International Colloquium on Sixteenth Century Science held in Royaumont, Paris, in 1957; International Symposium of the History of Science held in Pisa and Vinci in 1958; the International Ibn Sinâ and Nasiruddin al-Tusi congresses held in Tehran in 1954 and 1956; the millennial commemoration of Fârâbi’s death held in Istanbul in 1950; Turkish Historical Society congresses held in Ankara in 1956, 1961, and 1970; the Congress of Balkan Mathematicians held in Istanbul in 1971; the International Beyrûni Congress on the occasion of the one thousandth anniversary of his birth held in Pakistan in 1973; the Third World Conference on Education held in Istanbul by the World Council for Curriculum and Instruction in 1977; the International Symposium on the Observatories in Islam held in Istanbul in 1977 on the occasion of the four hundredth anniversary of the foundation of the Istanbul Observatory of Murad III; International Congress of the History and Philosophy of Science held in Islamabad, Pakistan, 8 to 13 December 1979; Conference on the Contributions of Islam to the Culture and Civilisation of Mankind and its Role in the Future, held in Islamabad, Pakistan, 7 to 10 March 1981; Science Polity in Islam held in the same year in Pakistan on the occasion of the one thousandth and four hundredth lunar year of the Hijra; International Symposium on the occasion of the one thousandth anniversary of Ibn Sînâ’s birth held in Kuala Lumpur, Malaysia, June 29 to July 1, 1981; Symposium on Hunting, Food Gathering and Food Production Types of Economy of the Neolithic Cultures in Central Asia held in Dushanbe, Tajikistan, between April 7-11, 1982; first National Symposium on History of Turkish Science, ‘The Ottoman Scientific and Professional Associations’ (3 -5 April 1987), organised by the Second Chair of History of Science established by the author of this article at the Faculty of Arts, Istanbul University in 1984 (later this became the first independent department in Turkish universities leading to a B.A. degree in history of science in 1989); Colloquium on the history of mathematics held by the Centre international de rencontres mathématiques in Marseille, 16-21 April 1984.

Figure 3: Front cover of Aydin Sayili’s book The Observatory in Islam (Ankara, 1988).

During the academic years of 1952-1953 and 1956-1957 Professor Sayili did research in the richest libraries of the United States with scholarships of ten months and eleven months granted by the Government of the United States and Ford Foundation.

Sayili received invitations from Harvard University, State University of New York in Albany and American University in Beirut to teach history of science courses in these universities. He declined these offers, however, in order to fulfil his duties and responsibilities in Ankara.

Professor Sayili was the tutor of only three PhD students during his long years of teaching in Ankara University. Two of them studied with him while he was still active; the third one started at the end of his career and later completed her PhD under the supervision of Professor Sayili’s first student. The first, retired Prof. Sevim Tekeli, who was his successor as the head of the chair, mainly represents the history of astronomy; the second, Prof. Esin Kahya represents history of natural sciences and medicine; and the third, Dr. Melek Dosay, is a lecturer in the field of history of mathematics.

Sayili knew English, French, German, Persian and Arabic. He has more than 100 books and articles published in scholarly journals. Most of them are in Turkish, English and Persian. Two of his books are in English. His first publications date back to his student days at Harvard University. At that time, his research work was mainly connected with his PhD thesis, the “Institutions of Science and Learning in Medieval Islam”, although he also undertook some research work in other subjects as well. But as a consequence of this, one general topic on which he did considerable work, beginning with his doctoral dissertation, has been the astronomical observatory, and additionally, the madrasa, the hospital, and the library in Islam.

In his book on the observatory in Islam, Sayili showed that the observatory as an astronomical institution was born in Islam. This stemmed from the characteristics of the world of Islam and its dependence on astronomy in the conduct of religious and lay affairs. This book also claims to show that the observatories of Eastern Islam served as prototypes and models for the early European observatories.

In this book, Professor Sayili has proved that the so-called Muqattam Observatory of Al-Hakim in Cairo, to which there are quite widespread references especially in European works during a period of nearly two hundred years, was in truth non-existent. Sayili has also fixed the specific location of the Damascus Observatory of Al-Ma’mun and of the Malikshah Observatory, which was for the first time discovered to be in Isfahan. He gleaned fragmentary but detailed information about Ma’mun’s observatories in the writings of Habash al-Hâsib, Beyrûnî and Ibn Yûnus, and thanks to these, it was possible to clear the relationship between the Baghdad and Damascus Observatories of Ma’mun – the somewhat strange situation that these two earliest and shortest-lived of Islamic astronomical observatories were seemingly contemporary or simultaneous.

This book sheds light on the evolution of the observatory in Islam from the standpoint of organisation, range of work, richness and efficiency of equipment, length of life, type or nature of financial support, and the connection of the observatory with the teaching of astronomy and different branches of mathematics. Aydin Sayili showed for the first time that the astronomers of Ma’mun made daily observations of the sun and the moon throughout a year. Later medieval astronomical sources of Islam also refer to this methodological aspect of astronomical research work. It is reminiscent of Tycho Brahe whose observatory building activity and astronomical instruments form a direct continuation to those of the Turkish-Islamic World of Eastern Islam. The Observatory in Islam was first printed by Turk Tarih Kurumu (Ankara, 1960) and reprinted in the United States in 1981 by Arno Press.

Sayili has also more specific publications on the Maragha, the Ghazan Khan, the Samarkand and the Istanbul Observatories, as well as on some other relatively minor institutions of a similar nature.

The prevalent impression was that the Istanbul Observatory of Murad III was demolished before any work had started to be done in it. Sayili, in his article titled “Ala al Din al-Mansur’s Poems on the Istanbul Observatory” showed that these poems contain clear assertions to the effect that the Istanbul Observatory witnessed some important scientific activities. This document indicates that the staff of the Istanbul Observatory comprised sixteen astronomers although only the name of one has reached us, and also that there was a “small library” attached to this institution.

George Saliba, in his article “The First non-Ptolemaic Astronomy at the Maragha School” (Isis, 70 [1979], 571-576), referring to The Observatory in Islam, quotes from it three passages taken from the Kitâb al-Hay’a of Al-‘Urdi, using them to identify for the first time correctly a certain Bodleian manuscript of an unspecified author. He also fully agrees with the estimate set forth in The Observatory in Islam that the Kitab al-Hay’a was written before the foundation of the Maragha Observatory. We should add that Sayili drew the attention of the historians of science and astronomy to the statement of a relatively little studied source to the effect that the Ilkhânî Tables of the Maragha Observatory were largely based on the Tables of Ibn al-A’lam and Ibn Yunus. This point has proved to be correct.

Sayili has published only parts of his work on the hospital. Most of this work is related to his PhD thesis and Sarton refers to this part in his Introduction to the History of Science (vol. 3, part I [1947], 293; part II [1948], 1248-1249). He refers in the same work to Professor Sayili’s article on Turkish medicine (ibid, 1217, 1226). (See also Isis, 40 [1949], 382.)

Figure 4: Aydin Sayili and George Sarton. Courtesy of Dr. Hüseyin Gazi Topdemir.

Sayili’s earliest book titled Science is the Truest Guide in Life is inspired by an aphorism of Atatürk and concerns the popularisation of science. The book puts forth the idea that man can ameliorate his life and find solutions to individual and societal problems only by benefiting from technology supported and guided by science. Thus, the growth of civilisation ensues.

On the other hand, science is responsible not only for the material aspects of civilisation. It is also the main force that accounts for constructive change, material and spiritual improvement and development in human life. The more direct influence of science on human life is seen through applied science and technology; indirectly it influences human life through the intellectual culture sector of our culture or civilisation.

Reviews of this book appeared in the Turkish journal ilk Ogretim (14 [1 August 1949, No. 275-2771, 3622, 3624) and in Isis (40 [1949], 286). Halil Inalcik referred to it in his article “Atatürk ve Türkiye’nin Modernlesmesi (Belleten, 27 [1963], 630) and particularly to the idea put forth in it to the effect that science brings dynamism to human societies and that it is indifferent to the boundaries of language, race or religion.

Sayili was a truly loyal, sincere and devoted follower of the ‘Kemalist’ understanding and ideology. This is evident in his above book, his more recent articles on the relationship between man, society and science in Turkey as well as the relationship of Ottoman Turkey with modern science and particularly his articles published in the periodical Erdem of which he was the editor in his last years.

Aydin Sayili had lately focused on the general subject of the fundamental place of science in human life and on man’s unceasing activity of forging ahead with the creation of better and stronger civilisations. He treated this subject in greater detail in relation to the theme of “Turkish as the language of science and learning” as well as in the context of the Turkish movement of Westernisation. Professor Sayili’s interest in Turkish as a language of science and culture goes back to his student days. In fact, he had helped Professor Sarton in this regard, as is evident from the latter’s acknowledgements (Introduction to the History of Science, vol. 3, part I [1947], 29, 104, 972, 1014).

The translation of books on science, philosophy, and medicine from Arabic into Latin during the twelfth century brought an end to the Dark Ages in Western Europe and led to the so-called Renaissance of the Twelfth Century. Sayili defended the view that the introduction of ideas and scientific knowledge from Islam into Western Europe continued after this initial ‘renaissance’ in a more subtle manner and limited measure until the seventeenth century. Thus, the Islamic world had appreciable influences in some of the first phases of the European scientific revolution accomplished by men like Copernicus, Galileo and Harvey. Ottoman Turkey also established contacts with Europe as early as the fifteenth, sixteenth and seventeenth centuries not only in technology and fine arts, but also in scientific and intellect matters.

Sayili has treated these questions in his articles “Islam and the Rise of the Seventeenth Century Science”, “Murad III’s Istanbul Observatory, Terrestrial Globe and Cultural Contact with Europe” and has touched upon this question in his book The Observatory in Islam, and in his other publications.

Sayili has also tried to establish the view that one of the firstborn and most ancient of human activities is science. According to a widespread view, science was born in Greek antiquity and that science came into being in the true sense of the word and in a somewhat limited range of its meaning only with the Renaissance, namely in the sixteenth century. Professor Sayili attempted to show that according to concrete facts and evidence, science had an independent existence side by side with religion, magic and technology in pre-Greek antiquity.

In this general perspective, the historical importance of the pre-Greek sciences of Egypt and Mesopotamia increase. This is particularly true of Mesopotamia, firstly because Mesopotamians had a much more advanced knowledge of mathematics and astronomy in comparison with the Egyptians; secondly, it seems that the Greeks have borrowed or learned much more from Mesopotamian science than that of the Egyptians. The situation changes perhaps greatly as regards medicine. It is necessary to underline the importance of these older civilisations in the emergence of the Greek scientific achievement because this issue has long been neglected. Professor Sayili attempted to bring together diverse examples of this subject in some of his publications.

Aydin Sayili also had a more or less permanent interest in the cause of the decline or stagnation of scientific activity and interest in Islam. From about the beginning of mid-eighth century onwards, there was a remarkable activity in the Islamic world to translate Greek works of science, philosophy and medicine. These systematic efforts did not continue in the later periods, however. Sayili tackled this problem by emphasizing aspects of it that can be related to intellectual culture, to causes linked with the phenomenon of decline. In order to have some control over the conclusions reached, he makes comparisons with late medieval Europe on the one hand, and with the experiences related to the movement of Westernisation, on the other.

One central problem here is the question of the degree of reconciliation that can be reached between philosophy and religion. If the peaceful coexistence of philosophy and religion is realised this would foster a scientific world view in the faces of mystical and magical counter views. A fundamental fact is that if scientific and philosophical knowledge were transmitted from generation to generation with an intensity higher than a threshold value, then scientific knowledge should be bound to continue and advance and grow with some degree of impetus, although small. Thus, provided the survival of a scientific or rational world view is somehow guaranteed, the situation boils down to the problem of organizing schools of higher education or systems of teaching in the so-called intellectual or secular sciences. Sayili’s work in these fields showed that in all these respects the scientific progress achieved by Islam was important, but not in a continuous and increasing way. However, Islam was helpful to late medieval Western Europe in these respects.

Sayili also treated the following topics in his works: the relationship between philosophy, including the secular sciences, and religion; the place of the secular sciences in the schools of higher education in Islam and the transmission of the knowledge of the secular sciences and medicine in general.

Another topic to which Aydin Sayili devoted attention is the role of the Turks in the scientific and intellectual achievements in the world of medieval Islam. He cites the importance of the Turks in the introduction of the use of a form of rag paper into the Islamic world. They also had a prominent role in the establishment of the madrasa system as well as the budding of hospitals and observatories. The hospital and the astronomical observatory had an active role in the dissemination of medical knowledge and astronomy as well as the spread of the natural and mathematical sciences.

Figure 5: Front cover of Aydin Sayili’s book Turkish Contribution to Scientific work in Islam published in the Turkish review Erdem, 3rd special issue, vol. 9, no. 27.

Professor Sayili defended the thesis that the contribution of the Turks to the world intellectual history in terms of a scientific and cultural movement was substantial. This thesis rests, at least partly, on the presence of an indigenous Turkish population not only in Central Asia proper, but also in the regions right to the east and northeast of Persia, at the time of the conquests of the Arab armies in these areas. On this subject Sayili has written articles in collaboration with Professor Richard N. Frye (“Turks in the Middle East before the Seljuqs”, Journal of the American Oriental Society, 63 [1943], 194-207; “The Turks in Khurasan and Transoxania at the Time of the Arab Conquests”, Muslim Work, 35 [1954], 308-315). Various scholars interested in this field referred to this article.

It is a well-known fact that these north-eastern regions of Islam had an extraordinary production of intellectual and scientific works in Islam. A number of well-known thinkers and scientists originated from these regions of Central Asia. Although it is often difficult to pinpoint their nationalities, a large number among them must have been Turkish. Another important contribution of the Turks was that they had a pioneering role in laying the intellectual foundations of the Islamic culture and civilisation and participated in Islam’s profound interest in scientific pursuits particularly in its initial and formative phases. Sayili has done some work especially on one such early Turkish scientist, namely, Abdulhamid ibn Turk.

Scientific activities by Turks continued throughout the ages. Qadizade and Ulugh Bey of the first half of the fifteenth century are remarkable examples of scholars who pursued such activity. It seems that Turks also played an important role in the dissemination of knowledge from Eastern Islam to Europe during the late Middle Ages and early modern times, as stated above. Finally, when Europe made great strides in sciences and industry, the Turks made a clear decision to adopt Western institutions of education and learning and to benefit from European scientific knowledge and methods of objective thinking. Indeed, outside of Europe, Ottoman Turkey was the first example of such Westernisation. Professor Sayili devoted some articles and papers to this subject.

In his article, “Higher Education in Medieval Islam” Sayili tried to show that the madrasa in the Islamic world, an institution of higher education, which probably set the model for the European medieval university, was officially created during the reigns of the Turkish Seljuk rulers such as Alp Arslan and Malikshah. Moreover, its initial and formative stages of development occurred in regions to the north and east of Iran which were mostly under Turkish rule and where a considerable part of the population was made of Turkish elements. G. Sarton refers to this publication in Isis, 40 (1949), p. 382, and Shigeru Nakayama (in his article “The Possibility of Scientific Revolution in the East, Specifically in the Case of Astronomy” (in Japanese) in the Japanese Journal Scientific Revolution (1961), p. 168).

Figure 6: Front cover of Logical Necessities in Mixed Equations By cAbd Al-Hamîd Ibn Turk and the Algebra of His Time by Aydin Sayili (Ankara: Turk Tarih Kurumu Basimevi, 1962). Click here for the online publication on www.MuslimHeritage.com.

In history of mathematics, Sayili’s work on Abdülhamid ibn Turk, an early ninth century mathematician, definitely established that Al-Khwarizmi did not originate his well-known geometric methods of solution of second degree equations and that his book was not the first monograph on algebra. However, some scholars prefer to give priority to Khwarizmi (see Roshdi Rashed, “L’idée de I’algèbre selon Al-Khwarizmi”, Fundamenta Scientiae, 4, No. 1 [1983], 87-100, and also the reference to Fuat Sezgin in the next paragraph). Sayili also published for the first time a letter by the ninth-century mathematician Thâbit ibn Qurra where he elaborately discussed the generalisation of the Pythagorean Theorem.

Both of the above works of Professor Sayili aroused interest among historians of mathematics. C. B. Boyer (Isis, 55 [1964], 68-70) and Christopher J. Scriba (his, 57 [1966], 56-66) tried to find the earliest references in Western Europe to the theorem propounded by Thâbit ibn Qurra. B.A. Rosenfeld and A. T. Grigorian cite it in the Dictionary of Scientific Biography (vol. 13 [1976], 293). C. B. Boyer dwells on this theorem and refers to Abdülhamid ibn Turk’s algebra in his History of Mathematics (1968; p. 257-259).

Figure 7: Two Turkish publications of Professor Sayili: the review Erdem (Ankara) [2nd special issue, vol. 9, no. 26] and Misirlilarda ve Mezopotamyalilarda Matematik, Astronomi ve Tip Adli Eserinin Muhtasari (the Abridged version of Mathematics, astronomy and medicine in Egyptians and Mesopotamians) of Aydin Sayili. Published by Mübahat Türker-Küyel (Ankara, 1996).

A Persian translation of Abdulhamid ibn Turk’s Arabic text was published by Professor Ahmed Ârâm (Risâla dar Jabr wal muqabala, Ta’lif-i Abu’l-Fadl Abdulhamid ibn Wâsit ibn Turk ibn Jaylî, Majalla-i Sukhan-i ‘ilmî No. 11 and 12, series [dawra] 3, 1342 SH (1968). Abulqasim-i Qurbânî too in his Riyâzidânân-i Iran ez Khwârazmî tâ Ibn-i Sînâ refers to Sayili’s work on Abdulhamid ibn Turk (Tehran, 1971; pp. 30-31). Fuat Sezgin dwells on this work as well (Geschichte des arabischen Schrifttums, 5 [1974], 24 1-242). Another work by Sayili on pure mathematics is about a solution found by the tenth-century mathematician and astronomer Al-Qûhî for the classical problem of Greek geometry, the trisection of the angle. A fourth article is titled “Beyruni’s Letter on Abu Mansur’s Proof of the Sine Theorem” (Beyrunî’ye Armagan (Ankara, 1974), 169-207).

A review of Sayili’s book on Abdülhamid ibn Turk appeared in Revue d’histoire des sciences (1 8 [1965], 123-124). Al-Qûhi’s trisection of the angle is cited by Ivonne Dold-Samplonius (Dictionary of Scientific Biography, vol. 11 119751, 241) and by Abulqasim-i Qurbani in his above-mentioned book (pp. 203, 205, 212-213). Sayili had given a preliminary report about Thâbit ibn Qurra’s generalization of the Pythagorean theorem first in a speech delivered at the History of Science Society’s annual meeting held in New York City (December 1956) in conjunction with AAAS annual meeting. In an account of this meeting in the American Historical Review (62 [1957], 797), the author cites this paper as one of the “highlights” of the meeting.

Al-Qûhî’s attempted proof of the possibility of infinite motion in finite time represented a venture to introduce a purely mathematical approach for the solution and clarification of mechanical and physical problems. Attempts of similar nature were seen in the sixteenth and later centuries in Western Europe, an early and typical example being that of Giovanni Battista Benedetti. This work of Al-Qûhî is cited in the article about him in the Dictionary of Scientific Biography (vol. 11 [1975], 241).

In the field of the history of astronomy, Sayili has dealt with the difficult question of the prediction of a solar eclipse (585 B.C.E.) by Thales. He claimed that contrary to the contentions of some chief authorities in this field, Thales must have made this prediction. But, according to Sayili, by prediction we should understand a forecast or prophecy which may come true although its “truth or cogency is not guaranteed in any way”. He dealt with this question in his Turkish book on pre-Greek science titled Mathematics, Astronomy and Medicine in Ancient Egypt and, Mesopotamia (Ankara, 1966; pp. 393 -407). Certain articles appeared after this work of Sayili was published, holding a favourable attitude to the thesis that Thales actually made this prediction (Willy Hartner’s article in Centaurus, 14 (1969), 60-71, and another by Asgar Aaboe in Journal for the History of Astronomy, 3 [1972], 105-118).

Sayili has discovered a book on astronomical instruments by the eleventh century scientist Al-Khâzînî in the Sipahsalar Library of Tehran. Historians of astronomy have referred to this work since about 150 years ago and it is mentioned by the sources. However, it was considered to be lost since no one could locate its place. This book was artificially merged with two others; a shorter part of it was bound in one volume and the rest in another. E.S. Kennedy in the Journal of Near Eastern Studies (20 [1961], 107) and Robert E. Hall in the Dictionary of Scientific Biography (vol. 7 [1973], 336, 348, 350) refer to this publication.

Professor Sayili wrote a book on Copernicus and a shorter Turkish version of it, which comprises the greater part of a volume, prepared in commemoration of the five-hundredth anniversary of Copernicus’ birth. His English work titled Copernicus and His Monumental Work was reviewed in Archives internationales d’histoire des sciences (26 [1976], 182-183). In the above works, he held the view that Copernicus hit upon the solution of longstanding questions about certain enigmatic relations or ties between solar and planetary motions. The Babylonians treated different phenomena concerning the planets, such as retrogradations and heliacal risings as independent phenomena. The Greeks integrated such phenomena into the planetary motions as parts and elements of these motions, but the fact that the retrogradation periods of all planets seemed to be conforming to the annual motion of the Sun remained unknown. Identifying all these retrograde motions with the revolution of the Earth around the Sun, Copernicus solved the enigma of this common feature of these otherwise different stellar motions. Sayili also added new evidence to support the thesis that Copernicus was substantially influenced by the Islamic world, and he speculated on the possibility that Istanbul, the Ottoman capital, was instrumental in the transmission of this influence.

Figure 8: Front cover of Aydin Sayili’s book Copernicus and his Monumental Work (Ankara, 1973)	Figure 9: Front cover of Fârâbî’s article on Vacuum, edited and translated by Necati Lugal and Aydin Sayili.

There are brief references to Sayili’s article on Habash al-Hâsib in A. Qurbâni, Riyâzidân-i Irânî ez Khwârazmî tâ Ibn-i Sînâ (pp. 46-49) and Isis (49 (1958), 228). Short bibliographical references to Sayili’s article on Al-Khâzini and Alauddin Mansur’s poems are found also in the same volume of Isis (pp. 227, 228). A.P. Youshkevitch and B.A. Rosenfeld referred to Sayili’s book on Ghiyath al-Din al-Khashi and Ulugh Bey’s scientific circle in the Dictionary of Scientific Biography (vol. 7 (1973), 261).

Sayili has done work on the status and popularity of astrology in the Middle Ages. The first stages of this work, which in a more developed form has been included in the first chapter of his book The Observatory in Islam, has been referred to by Sarton in his Introduction to the History of Science (vol. 3, part 1 [1947], 263-264). Further references to some of his publications on the history of astronomy may be found in Joseph Needham’s Science and Civilisation in China (vol. 3 [1959], 333; vol. 4, part 3 (1971), 814).

Professor Sayili also did research in the field of the history of optics, especially on the explanation of the rainbow by Aristotle and also by Al-Qarafî. Carl B. Boyer, in his articles “Aristotelian References to the Law of Reflection” (Isis, 36 [1916], 92-95), “The Theory of the Rainbow: Medieval Triumph and Failure” (Isis, 49 [1958], 379), and in his book The Rainbow (New York, 1959, pp. 324, 325, 327, 328, 335, 356, 358), George Sarton, in his Introduction to the History of Science (vol. 3, part I [1947], 709) and in his book A History of Science, Ancient Science Through the Golden Age of Greece (1952, p. 518), and H.J.J. Winter, in “The Optical Researches of Ibn al Haitham” (Centaurus, 3 [1954], 205-210), refer to these publications. Sarton also refers to Sayili’s work on optical experiments of Theodoricus of Freiberg, and considers them among the most remarkable examples of their kind encountered in medieval times (Introduction to the History of Science, op. cit., 706). He said in particular that Ibn al-Haytham was a greater authority than Ibn Sinâ in the field of optics was and, seemingly, their ideas about the explanation of optical phenomena generally differed. Professor Sayili found an exception to this situation, however, in the lecture he presented to the ‘Third International Congress on Turkish Culture’ (Ankara, 25-29 September 1993).

References

• Fahri Coker, Türk Tarih Kurumu: Kurulus Amaci ve Calismalari (Ankara, 1983), 694-700.
• Ekmeleddin Ihsanoglu, “Aydin Sayili and His Scholarly Contribution (1913-1993)”, a foreword to the Arabic edition of Prof. Sayili’s The Observatory in Islam, trans. by Abdullah al-Omar, Kuwait University (in press).
• ILESAM 1993 Hizmet Seref odülleri ilesam Haber Bulteni, p. 7.
• Sevim Tekeli, “Hocamiz Ord. Prof. Dr. Aydin Sayili’yi Ugurlarken”, Arastirma: Dil ve Tarih- Cografya Fakültesi Felsefe-Sosyoloji-Psikoloji Bilimleri Dergisi, 13 (1 99 I), 1- 1 1.
• In addition to the above, I wish to mention, “Brief Biography and Account Concerning the Scientific Activity of Professor Aydin Sayili,” prepared by the late Professor Sayili himself and given to me personally.

* HH. Professor Ekmeleddin Ihsanoglu is the Secretary General of the Organisation of the Islamic Conference (OIC), Jeddah. Past Director General of the Research Centre for Islamic History, Art and Culture (IRCICA) in Istanbul, and past President of the International Union of History and Philosophy of Science, Division of History of Science.