Al-Biruni

Al-Biruni was one of the most learned of Muslim scholars and scientists. His interests were very wide as he labored in almost all the branches of science known in his time. The spectrum of his scientific output includes a wide range of sciences, from applied and theoretical mathematics to pharmacology, geology, mineralogy, and history.

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Figure 1: An artistic impression of al-Bīrūnī (Copyright MuslimHeritage.com).

Abū al-Rayhān Muhammad ibn Ahmad al-Bīrūnī was born in 362/973, in the suburb of Kath, capital of Khwārazm (today Bīrūnī), now a region of Uzbekistan on the southern shores of the Aral sea. He died in 1048 in Ghazna (now in Afghanistan), where he lived for a long time, in the court of the Gaznavid state, where he was introduced by Sultan Mahmud al-Ghaznawi.

Mas'ūd, the son of the Sultan Mahmūd of Ghazna, was a great devotee of astronomy, and loved sciences. He was talking to al-Bīrūnī once about the difference of the lengths of the days and the nights on earth, and wanted to know why this happened. Thus, al-Bīrūnī wrote for him a treatise based on observations of the nights and days, and added another book on the movements of the planets, and completed his famous Canon, Al-Qânûn al-Mas'ûdî which he dedicated to Sultan Mas'ûd. To thank him, the sultan sent him an elephant loaded with silver coins. Al-Bīrūnī refused the gift, and returned all the money to the treasury, assuring the envoy and the sultan he could live without such wealth [1].

At an early age of his career, at the court of the sultan of Khwarizm, Yaqut al-Hamawi tells us, the Sultan called on him, whilst al-Bīrūnī was still in his chamber. As al-Bīrūnī was getting late, the Sultan informed him he was going to go up to his chamber; then al-Bīrūnī came down, excusing himself. To which the sultan answered: "Science is one of the highest occupations; all mortals go to it; it is not science which goes to them."

Then he added: "If it was not for etiquette, I will not have called you, because science is high enough by itself and cannot rise any higher [2]."

Al-Bīrūnī, lived and worked for most of his life at the court of Sultan Mahmûd, and his son, Mas'ûd. He accompanied Mahmûd on his campaigns into India, which lasted for about thirteen years (1017-1030). It was during those campaigns that Al-Bīrūnī learned Sanskrit and took extensive notes, which he later published in what is now considered the most authoritative account of medieval India [3]. After Mahmud's death in 1030 and that of his son Mas'ūd in 1040, Al-Bīrūnī survived and lived to a ripe old age.

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Figure 2: Al-Bīrūnī commemorated in Egyptian, Soviet, Afghan and Iranian stamps.

Al-Bīrūnī's production exceeds 146 titles in more than twenty different disciplines, ranging from astronomy to mathematics, mathematical geography, chronology, mechanics, pharmacology, mineralogy, history, literature, religion, and philosophy. Only 22 works have survived the ravages of time; and only a dozen or so of these have been published [4].

Though al-Bīrūnī dedicated himself to astronomy, he excelled also in mathematics in an age when mathematics consisted of arithmetic, geometry, physics and music [5]. Other than being the master of geodesy, that is mathematical geography, al-Bīrūnī made simplified stereographic projection similar to that first published by G. B. Nicolosi di Paterno in 1660 [6]. However, as Max Meyerhof observed earlier this century, most of al-Bīrūnī 's mathematical works and many other writings have not been published yet [7].

Al-Bīrūnī is an objective scholar, assiduous in research, critical in the scrutiny of traditions and texts (including the Gospels), precise and conscientious in statement, frequently admitting his ignorance, and promising to pursue his inquiries till the truth should emerge [8]. He strictly followed the holy injunction to "speak the truth, even if it were against yourselves [9]." In the preface to the Vestiges of the past (Kitab al-athar al-baqiya 'ani-l-qurun al- khaliya) [10] he wrote: "We must clear our minds . . . from all causes that blind people to the truth –old custom, party spirit, personal rivalry or passion, the desire for influence [11]."

For him, "truthfulness enjoined by the Holy Scriptures on mankind possesses its own intrinsic beauty just like justice, while liars give birth to all kinds of vices which serve to ruin the world and mankind [12]."

He also stuck by the principle, that it is crucial to obtain information from primary source rather than secondary sources. A prerequisite for a scholar was that he ought to be free from all bias and prejudices, selfish interests, ideas of profiteering and from the complexes of a conqueror. A historian should free himself from all such associations and drawbacks which inhibit him from observing the truth [13].

His work Chronology (Al-Athar) combines literary and historical sources of medieval sects and nations with the astronomical lore about their calendars, feasts, and astronomical parameters used in their rituals. For example his work Tahdid was about the demarcation of the coordinates of cities, was written so as to determine the qibla with the aid of mathematics, from anywhere in the world. Al-Bīrūnī also determined the local meridian and the coordinates of any locality.

Al-Qanun Al-Mas'udi, al-Bīrūnī's great astronomical treatise, is a most extensive astronomical encyclopaedia, slightly short of 1,500 pages. In it he determines the motion of the solar apogee, corrects Ptolemy's findings, and is able to state for the first time that the motion is not identical to that of precession, but comes very close to it. In this book, too, al-Bīrūnī employs mathematical techniques unknown to his predecessors that involve analysis of instantaneous motion and acceleration, described in terminology that can best be understood if we assume that he had "mathematical functions" in mind.

Al-Bīrūnī's works respond in great part to his scientific curiosity, and also to his duties to the faith; his Tahdid Nihayat al-amâkin li-tashîh masâfât al-masâkin (The demarcation of the coordinates of cities) [14] was written so as to determine the qibla. For Muslims inorder to pray they must face in the proper direction, one has to know with some precision the longitude and latitude of Mecca, the city toward which one must face. Once that is determined, the values are applied to a spherical triangle, and the angle from the local meridian to the required direction of Mecca can be determined. The problem admits of more than one method of solution, and Al-Bīrūnī did his share in supplying the various methods in this book [15].

The same link between science and faith is found in his work: Shadows (Ifrâd al-maqâl fî 'amr al-zilâl). This treatise, written sometime after 1015, after discussing the linguistic application of the word zill (shadow) and the astronomical phenomena associated with it, goes on to give a definition of shadow functions (tangent and cotangent), and to explain in great detail the ensuing identities, theorems, and special applications [16]. He then applies himself to the problem of determining the time of day from shadows, and quickly exploits that to connect his discipline with the time of the Muslim daily prayers that are astronomically defined [17].

Al-Bīrūnī occupied himself as well with the empirical question of determining the local meridian and the coordinates of any locality. Once that was done, he applied this information to problems of distances between cities, a use that was of great political and economic value [18].

The scientific spirit of Al-Bīrūnī is obvious in his work on the Elements of Astrology (Kitâb al-tafhîm li-'awâ'il sinâ'at al-tanjîm) [19]. By his own admission this book is the most comprehensive of his works on astrology. It was written at the request of Rayhana, the daughter of al-Hasan of Khwarizm, in a question-and-answer style, and includes a long introduction on preliminary principles of geometry, arithmetic, astronomy, astronomical problems in relation to the earth, chronology, and the astrolabe. This introduction takes up some 346 paragraphs of the total 530, well over half the book [20].

However, there is enough evidence to suggest that Al-Bīrūnī's heart was not in astrological doctrines. At several points in this text on astrology, he warns his reader against excessive belief in astrology. Moreover, the astrological sections of the Masudi Canon are also prefaced by warnings against belief in astrology. At one point he goes so far as to say that he discussed astrology in detail in order to warn the intelligent man away from it. Al-Bīrūnī's only book that would have elaborated his attack against astrology is unfortunately known to us only by name, and seems to have been lost during his lifetime. But the title, Warning Against the Craft of Deceit, meaning astrology, leaves very little doubt as to al-Bīrūnī's position and belief [21].

Al-Bīrūnī spent many years studying India, its peoples, languages, faiths, cultures, and castes. In 1030 he published his masterpiece, History of India (Tahqîq mâ li-'l-Hind) [22]. At the outset he sharply distinguished between hearsay and eyewitness reports, and classified the varieties of "liars" who have written history. He spent little space on the political history of India, but gave 42 chapters to Hindu astronomy, and eleven to Hindu religion [23]. He speculated on the possibility that the Indus valley had been once the bottom of a sea, and explained the workings of natural springs and artesian wells by the hydrostatic principle of communicating vessels [24]. In his description of India, Al-Bīrūnī describes distant parts as the frontiers of Nepal and Tibet, and how from the highest summits, India appears as a darkened expanse of land under the fog, the mountains underneath looking like small hills, and the Tibet appearing as a red mass [25].

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Figure 3: Among Al-Bīrūnī's chef-d'œuvres is his Al-Athâr al-Bâqiyah 'an al-Qurân al-Khâliyah (The Chronology of Ancient Nations and their History) depicted here in a rarest and exquisitely illustrated manuscript copy (MS Or 161) preserved at Edinburgh University Library. (Source)

Al-Bīrūnī's interest in minerals and other substances from a scientific point of view is equally advanced. He composed an extensive lapidary, describing a great number of stones and metals from the natural, commercial, and medical points of view [26]. He determined the specific gravity of eighteen precious stones, and laid down the principle that the specific gravity of an object corresponds to the volume of water it displaces [27]. His measurements correspond exactly to those we have today [28].

His Al-Qânûn al-Mas'ûdî [29] is a most extensive astronomical encyclopaedia, slightly short of 1,500 pages. In it he determines the motion of the solar apogee, corrects Ptolemy's findings, and is able to state for the first time that the motion is not identical to that of precession, but comes very close to it [30]. The work has the general outline of a zîj (astronomical handbook), but is much more detailed and analytical in its approach to observations and numerical tables. In this book, too, al-Bīrūnī employs mathematical techniques unknown to his predecessors that involve analysis of instantaneous motion and acceleration, described in terminology that can best be understood if we assume that he had "mathematical functions" in mind [31]. It is unfortunate that this text has not yet been translated and studied by modern scholars, for it not only promises to be of great importance to historians of Islamic astronomy but also may change our accepted ideas about the general history of mathematics [32].

Among the astronomical and philosophical issues that al-Bīrūnī hit upon, he discussed the hypothesis of the earth's motion. He took it for granted that the earth is round, noted "the attraction of all things towards the centre of the earth," and remarked that astronomic data can be explained as well by supposing that the earth turns daily on its axis and annually around the sun, as by the reverse hypothesis [33].

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Figure 4: Illustration by al-Bīrūnī of different phases of the moon, from Kitab al-tafhim. Source: Seyyed Hossein Nasr, Islamic Science: An Illustrated Study, London: World of Islam Festival, 1976.

Al-Bīrūnī also wrote treatises on the astrolabe, the planisphere, and the armillary sphere [34]. Although the astrolabe was the most famous instrument of medieval astronomer-astrologers, there is not a single known Muslim treatise in which one could find as thorough a discussion of its history and various types as that in the introductory part of this treatise on the astrolabe of al-Bīrūnī [35]. Abu al-Rayhan lists all the contemporary astrolabes that he knows of, and the theories underlying their construction. While discussing the astrolabe of Abu Sa'id al-Sizji (d. ca. 1024), he states that Sizji had constructed his astrolabe "employing the principle believed by some people that the apparent rising motion is due to the movement of the earth and not that of the heavens [as is traditionally believed]. I earnestly believe that this problem of whether the earth or the heaven is the one that moves is very difficult to determine and either motion is equally valid for geometricians and astronomers who employ mathematical lines exclusively. The final solution, however, concerns only the natural philosophers, for it is within their own domain of study [36]." Using the astrolabe and the presence of a mountain near a sea or flat plain, he calculated the earth circumference by solving a highly complex geodesic equation. He contributed to geometry by finding the solution of theorems that thereafter bore his name [37].

Al-Bīrūnī's was not especially keen to dwell on philosophical issues. Only once did he correspond with his contemporary Ibn Sina; and from a close reading of the contents of the questions that he asked Ibn Sina and the responses that he supplied, one feels that Al-Bīrūnī's heart and talent were somewhere else [38]. However, it is interesting to consider some of the issues raised in this exchange in order to have a good view on how the Muslims addressed issues with which the West could only catch up in our times, thus nearly ten centuries later. Al-Bīrūnī refers to this episode in the Chronology, which was probably composed near about 1000. Al-Bīrūnī could have sent the questions directly through a messenger. Some of the questions were:

- Aristotle has no sound reason for his supposition that the Heavens are neither heavy nor light.

- Aristotle's method of seeking support for his theories in the opinions of former thinkers (in respect of the idea that the universe had no beginning) is improper.

- Aristotle's reasons for rejecting the atomic theory are not sound and his own theory of the infinite divisibility of matter is no less open to objection.

- Aristotle is not justified in denying the possibility of the existence of other universes besides our own.

- Aristotle is not justified in saying that the Heavens move from the east, as the east is the right side. Right and left are merely relative terms.

- How is heat imparted through the rays of the sun and are the rays themselves material, or indicate a condition of something else?

- How does a round flask of glass, full of water, burn things opposite to it, while the same filled with other elements, e.g., the air, does not do so?

- Do all the four elements move to their centres or does only earth or water gravitate, while air and fire move from the centre to their enclosing spheres?

- What is the nature of vision? How do we see below the water?

- Why is only one quarter of the earth supposed to be inhabitable, while the other three quarters are equally capable of being so?

- Why do vessels break by the solidification of water?

- Why does ice float on water? [39]

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Figure 5: Al-Bīrūnī 's crater on the Moon (coordinates 17.9oN, 92.5oE, diameter 9 km).

Because of his great scientific stature, a controversy has arisen concerning al-Bīrūnī's national origin and allegiance. The controversy is a result of modern politics, and he has been claimed by several nations: the Soviet Union because he was born in what was until recent years the Soviet Central Asia, Iran because he spoke Khwarazmian, a kin dialect of Persian; Pakistan and Afghanistan because he lived a good a part of his life in Sind and near modern Kabul; the Arab nations because he wrote most of his works in Arabic. As a result his millenary celebrations in 1973 were held in more than one country, and he was honoured as the national scientist of each. It is in the introduction of the Pharmacology that al-Bīrūnī speaks of himself as being first and foremost a Muslim who thinks that of all the languages he spoke or learned, Arabic is the most suitable for scientific discourse, and that Persian is good only for evening entertainment [40].

Further reading and references

Works of al Bīrūnī

Bīrūnī, al-, The Chronology of Ancient Nations, English translation by C. E. Sachau. (London, 1879).

Alberuni's India, edit. C. E. Sachau (London, 1887).

Kitāb al-tafhīm. The Book of Instruction in the Elements of the Art of Astrology (London, 1934).

Kitāb al-Jamāhir fī ma'rifat al-jawāhir, ed. F. Krenkow (Hyderabad 1936).

Al-Qānūn al-Mas'ūdī (3 vols., Hyderabad, 1954-56).

Kitāb tahdīd nihāyat al-amākin, (Beirut 1967).

The Exhaustive Treatise on Shadows, transl. and commentary E. S. Kennedy (Aleppo 1976); Kitāb maqālid 'ilm al-hay'a (Damascus 1985).

In den Garten der Wissenschaft. Ausgewählte Texte ... übersetzt und erläutert von G. Strohmaier (Leipzig, 1988).

The book most comprehensive in knowledge on precious stones, engl. tr. H. M. Said (Islamabad, 1989).

Al-As'ilah wa'l-ajwibah (Questions and answers) (Kuala Lampur, 1995).

Commentaries and Literature:

Abattouy, Mohammed 2003. "Al-Bīrūnī". In: Lexikon bedeutender naturwissenschaftler. Edited by D. Hoffmann, H. Laitko et S. Müller-Wille. Heidelberg-Berlin: Spektrum Academischer Verlag, vol. 1, pp. 178-183.

E. S. Kennedy, "Al-Bīrūnī" Dictionary of Scientific Biography (vol. 2, New York 1970-80).

Id., Studies in the Islamic Exact Sciences (1983 Beirut).

G. Saliba, "Al-Bīrūnī and the Sciences of his Time." In: Religion, Learning and Science in the 'Abbasid Period, M. Young et al. (Cambridge University Press, 1991, 405-23).

S.H. Nasr, An Introduction to Islamic Cosmological Doctrines: Conceptions of Nature and Methods Used for Its Study by the Ikhwan Al-Safa, Al-Bīrūnī, and Ibn Sina (State University of New York Press, 1993).

End Notes

[1] According to Barron Carra de Vaux, Les Penseurs de l'Islam, Paris: Geuthner, 1921, p. 79.

[2] Ibid, p. 78.

[3] G. Saliba, "Al-Bīrūnī", Dictionary of Middle Ages, 13 vols., edited by Joseph Strayer, New York: Charles Scribner's Sons, vol. 2 (1982), pp. 248-52; at p. 248.

[4] Ibid.

[5] According to the classical division of sciences, as exposed by al-Farabi in Ihsa al-Ulum: See M. Bouyges, "Sur le De Scientiis d'al-Farabi", Mélanges de l'Université Saint Joseph, IX (1923-24): pp. 41-96.

[6] G.Sarton, Introduction to the History of Science, 3 vols.; The Carnegie Institute of Washington; 1927-48; vol. 2, p. 107.

[7] Max Meyerhof, "Science and Medicine", in The Legacy of Islam, edited by T. Arnold and A. Guillaume, Oxford University Press, 1931, pp. 311-55, at p. 332.

[8] W. Durant, The Age of Faith, Simon and Shuster, New York, 6th printing, 1950, p. 243.

[9] H. M. Said, A. Z. Khan, Al-Bīrūnī: His Times, Life and Works, Karachi: Hamdard Foundation, 1981, p. 178.

[10] The Chronology of Ancient Nations. An English Version by E. Sachau of the Arabic text of al-Athâr al-bâqiya... of al-Bîrûnî, or ‘Vestiges of the Past'. London, 1879.

[11] W. Durant, The Age of Faith, op. cit., p. 243.

[12] H. M. Said, A. Z. Khan, Al-Bīrūnī, op. cit., p. 180.

[13] Ibid, p. 181.

[14] The Arabic text was edited by J. Bolghakov and A. Ahmad, in Majallat ma'had al-makhtûtât al-'arabiya (Kuwait), vol. 8, 1962. The English translation was achieved by Jamil Ali: The Determination of the Coordinates of Positions for the Correction of Distances between Cities. Beirut: The American University of Beirut, 1967. For a thorough study, see A Commentary upon Bîrûnî's ‘Kitâb tahdîd al-amîkin', an 11th-Century Treatise on Mathematical Geography by Edward S. Kennedy (Beirut: The American University of Beirut).

[15] G. Saliba, "Al-Bīrūnī", op. cit., p. 249.

[16] Ibid, p. 250.

[17] Ibid.

[18] Ibid, p. 249.

[19] Al-Bîrûnî, Kitâb al-tafhîm li-'awâ'il sinâ'at al-tanjîm. Book of the Instruction in the Elements in the Science of Astrology, edited by R.R. Wright, London: Luzac, 1938.

[20] Ibid, p. 250.

[21] Ibid.

[22] Alberuni's India: An Account of the Religion, Philosophy, Literature, Geography, Chronology, Astronomy, Customs, Laws and Astrology of India About A.D. 1030, 2 vols; London: Trübner, 1887-88. Edition of the Arabic text and English translation with notes by C. Edward Sachau (reprinted in 1910).

[23] W. Durant, The Age of Faith, op. cit., p. 243.

[24] Ibid, p. 244.

[25] Barron Carra de Vaux, Les Penseurs, op. cit., p. 87.

[26] Kitâb al-Jamâhir fî ma'rifat al-jawâhir. The Most Comprehensive Book on the Knowledge of Precious Stones. Translated by Hakim Mohammad Said. Islambad: Pakistan Hijrah Council, 1989. English translation of the first treatise of minaralogy, which contains elaborate discussions on about fifty precious stones, metals and mineral substances.

[27] W. Durant, The Age of Faith, op. cit., p. 244.

[28] R.E. Hall, "Al-Khazini", in Dictionary of Scientific Biography, New York, vol 7, pp. 335-58.

[29] This very important text was published as: Al-Qânûn al-Mas'ûdî, Haydarabad: Da'irat al-ma'ârif al-'uthmâniya, 3 vols., 1954-56.

[30] G. Saliba, "Al-Bīrūnī", op. cit., p. 249.

[31] Ibid.

[32] Ibid.

[33] W. Durant, The Age of Faith, op. cit., p. 244.

[34] Ibid.

[35] G. Saliba, "Al-Bīrūnī", op. cit., p. 250.

[36] Ibid.

[37] W. Durant, The Age of Faith, op. cit., p. 244.

[38] G. Saliba, "Al-Bīrūnī", op. cit., p. 251. The text of this important scientific controversy on key issues of natural philosophy is reproduced in: Al-As'ilah wa-'l-ajwibah. Questions and Answers. Including the Further Answers of al-Bîrûnî and al-Ma'sûmî's Defense of Ibn Sînâ. Edited with English and Persian introduction by Seyyed Hossein Nasr and Mehdi Mohaghegh. Kuala Lampur: International Institute of Islamic Thought and Civilization, 1995.

[39] H. M. Said; A. Z. Khan, "Al-Bīrūnī: his Times", op. cit., pp. 105-106.

[40] G. Saliba, "Al-Bīrūnī", op. cit., p. 251.

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