ʿISĀ B. YAḤYĀ MASIḤI JORJĀNI, Abu Sahl, physician, philosopher, mathematician, and astronomer (d. after 925). Little is securely known about the life of this Christian scholar, since the surviving biographies and anecdotes are inconsistent and contradictory. Ẓahir-al-Din Bayhaqi (q.v.; Tatemmat Ṣewān al-ḥekma, pp. 90-91), for instance, claims that he was born in Jorjān, studied in Baghdad, and wrote his Ketāb taʿbir al-roʾyā (Dream interpretation) for the Kvārazmšāh Maʾmun b. Moḥammad (r. 995-997). But the testimony of Ebn al-Qefṭi (pp. 408-9) and Ebn Abi Oṣaybeʿa (col. 1, pp. 327-8), supported in part by Bar Hebraeus (col. 1, p. 176; see EBN AL-ʿEBRI), is that ʿIsā taught Ebn Sinā (Avicenna, q.v.) medicine, presumably at Bokhara in the 990s, though Ebn Sinā in his autobiography does not acknowledge him as his teacher (Gutas, p. 27). He is also said by the same sources to have been in Khorasan, presumably after the fall of the Samanids in 999, where he became prominent at the ruler’s court. Ebn Abi Oṣaybeʿa attributes this story to ʿObayd-Allāh b. Jebrāʾil (d. 1058); from 997 Khorasan was under the control of the Ghaznavid Sultan Maḥmud. However, ʿIsā must have been at the court of the Kvārazm-šāh at Gorgānj with such luminaries as Ebn Sinā and Abu Rayḥān Biruni (q.v.) in the early eleventh century, since he wrote his Ketāb al-ṭebb al-kolli (Complete medicine; Ullmann, p. 151) and his Ketāb fi aṣnāf al-ʿolum al-ḥekmatiya (Categories of the philosophical sciences) for Abu’l-Ḥosayn al-Sohayli, the minister of ʿAli b. Maʾmun (r. 997-1009; Gutas, p. 150), and his Resāla fi taḥqiq soʾāl al-mezāj (On the determination of the questions of health) and, according to Ebn Abi Oṣaybeʿa, his Resāla fī taḥqiq amr al-wabāʾ (On the determination of the matter of infectious diseases) (Sezgin, GAS VII, p. 389) for Abu’l-ʿAbbās Maʾmun b. Maʾmun (r. 1009-17).

The second tradition also reports that ʿIsā died at the age of forty; Eilhard Wiedemann claims that Ebn al-Qefṭi and Ebn Abi Oṣaybeʿa place his death in 400/1009-10, but in fact such information is not found in their biographies of ʿIsā. Others (e.g., Sezgin, GAS III, p. 326) place it in 401/1010-11, without citing any sources. We shall see below, however, that he was still alive when Biruni completed his Ketāb taḥdid nehāyat al-amāken in 1025. Neẓāmi ʿArużi (tr. Browne, pp. 119-21) relates a curious anecdote, according to which Maḥmud of Ghazna demanded that the Ḵvārazmšāh send him the philosophers at his court. Several, including Biruni, were eager to go, but Ebn Sinā and ʿIsā evidently refused; for Maʾmun dispatched them for refuge to Māzandarān in Ṭabarestān. They lost their way in a sandstorm, and, due to the excessive heat, ʿIsā expired in the desert. There seems to be no merit in this story, since Biruni stayed at Gorgānj until 1017, since Ebn Sinā and ʿIsā are both incongruously represented as practicing astrologers who predicted their own difficulties, and since Biruni refers to ʿIsā as still living in a book he completed in 1025.

ʿIsā’s acquaintance with Biruni is confirmed by the list of twelve works that ʿIsā wrote in Biruni’s name listed by the latter in his Resāla fi fehrest kotob Moḥammad b. Zakariyāʾ al-Rāzi (Kraus, pp. 45-46):

1. Ketāb fi mabādiʾ al-handasa (On the foundations of geometry). The only mathematical work mentioned in Sezgin, GAS V, pp. 336-37.

2. Ketāb fi rosum al-ḥarakāt fi’l-ašyāʾ ḏawāt al-ważʿ (On drawings of the motions in things having position).

3. Ketāb fi sokun al-arż aw ḥarakatehā (On the immobility or motion of the earth).

4. Ketāb fi’l-tawassoṭ bayn Aresṭuṭālis wa Jālinus fi’l-moḥarrek al-awwal (On the intermediate position between Aristotle and Galen concerning the Prime Mover).

5. Resāla fi dalālat al-lafẓ ʿala’l-maʿnā (On a word’s indication of meaning).

6. Resāla fi sabab bard ayyām al-ʿajuz (On the cause of the coldness on the Days of the Old Woman).

7. Resāla fi ʿellat al-tarbiyat allati tostaʿmal fi aḥkām al-nojum (On the deficiency of the education which is used in astrology).

8. Resāla fi ādāb ṣoḥbat al-moluk (On manners for companionship with kings).

9. Resāla fi qawānin al-sÂanāʿa (On the rules of the crafts)

10. Resāla fi dastur al-ḵaṭṭ (On the rules of calligraphy[?]).

11. Resāla fi’l-ḡazaliyāt al-šamsiya (On the risings of the sun).

12. Resālat al-narjesiya (On narcissism).


These works, some of which reflect Ebn Sinā’s interests, illustrate ʿIsā’s commitment to non-medical topics. Unfortunately, there exist no manuscripts of any of them.

Biruni’s appreciation of ʿIsā’s work in mathematics is indicated by his citing in the Taḥdid (p. 170) a letter from him in which he claims that the number of arrangements of combinations of the times of the observation of a lunar eclipse in two cities is 128,450,560,000; Biruni adds that ʿIsā had written to him recently to claim that he had found that some extra arrangements make the total a multiple of his previous result. Biruni began to write the Taḥdid at Ghazna in 1018 and completed it in 1025. In al-Āṯār al-bāqiya, written in 1000, Biruni (p. 63) quotes three verses of ʿIsā naming the months of the pre-Islamic Arabs (Ṯamud). Ebn Abi Oṣaybeʿa reports that he also wrote a Ketāb eḵteṣār ketāb al-Majesṭi (Compendium of the Almagest). Brockelmann (GAL I, pp. 273-74) mentions three other non-medical works by ʿIsā; a Ketāb al-arkān al-ʿālam (The basic elements of the world), a Ketāb mabaādeʾ al-mawjudāt al-ṭabiʿiya (Foundations of the natural creation), and a Ketāb talḵiṣ ketāb al-samāʾ wa al-ʿalām li Arisṭutālis (Abridgement of Aristotle’s On Heaven and the World). Nothing more is known of any of these.

Nor is much known of his medical works other than those previously mentioned beyond their manuscripts and a synopsis of the first item in the following list, even though ʿIsā’s biographers unanimously agree that he was the best physician among the Christians. The medical works are listed in Sezgin, GAS III, pp. 326-27:

1. Al-Ketāb al-miʾa fi’l-ṣenāʿat al-ṭebbiyya (Book of one hundred [sections] on the medical art; see G. Karmi, 1978).

2. Ketāb eẓhār ḥekmat Allāh taʿālā fī ḵalq al-ensān (Demonstration of the wisdom of God with respect to the physical constitution of men).


Gregory Bar Hebraeus (Ebn al-ʿEbri), The Chronography of Gregory Abū’l-Faraj . . . Barhe-braeus, ed. and tr. E. A. Wallis Budge, 2 vols., London, 1932.

Ẓahir-al-Din Bayhaqi, Tatemmat Ṣewān al-ḥekma, ed. D. Rafiq al-ʿAjam, Beirut, 1994.

Abu Rayhān Biruni, Ketāb al-āṯār al-bāqiya, ed. C. E. Sachau, Leipzig, 1923.

Idem, Taḥdid nehāyāt al-amāken, ed. P. Buljākuf (P. G. Bulgakov), Cairo, 1964.

Brockelmann, GAL I, pp. 273-74, and SI, pp. 423-4.

A. Dietrich, “al-Masīhī al Djur-djānī,” in EI ² VI, 1991, pp. 726-27.

Ebn Abi ʿOṣaybeʿa, ʿOyun al-anbāʾ, ed. A. Müller, 2 vols., Cairo, 1882.

Ebn al-Qefṭi, Taʾriḵ al-ḥokamā’, ed. J. Lippert, Leipzig, 1903.

D. Gutas, Avicenna and the Aristotelian Tradition, Leiden, 1988.

Isā b. Yaḥyā, Aṣnāf al-ʿolum al-ḥekmatiya, ed. M.-T. Dānešpajuh, Tehran, 1991.

G. al-Karmi, “A Medieval Compendium of Arabic Medicine: Abū Sahl al-Masīḥī’s ’Book of the Hundred,’” Journal of the History of Arabic Science 2, 1978, pp. 270-90.

P. Kraus, Epitre de Bērūnī, Paris, 1936. Neẓāmi ʿArużi Samarqandi, Čahār maqāla, Eng. tr. E. G. Browne as Chahár Maqála (Four Discourses), London, 1921; repr., London, 1978.

Sezgin, GAS III, pp. 326-27; V, pp. 236-37; VI, p. 241; and VII, p. 389. H. Suter, Die Mathematiker und Astronomen der Araber und ihrer Werke, Leipzig, 1900, p. 79 (no. 180).

M. Ullmann, Die Medizin im Islam, Leiden, 1970.

E. Wiedemann, “Zum Wunder des heiligen Feuers,” Zeitschrift des Deutschen Palāstina-Vereins 40, 1917, 248-51; repr. in his Gesammelt Schriften, 3 vols., Frankfurt-am-Main, 1984, II, pp. 865-68.

(David Pingree)

Originally Published: December 15, 2006

Last Updated: March 30, 2012

This article is available in print.
Vol. XIII, Fasc. 6, pp. 609-610

Cite this entry:

David Pingree, “ʿISĀ B. YAḤYĀ MASIḤI JORJĀNI,” Encyclopædia Iranica, XIII/6, pp. 609-610, available online at http://www.iranicaonline.org/articles/isa-b-yahya-masihi-jorjani (accessed on 30 December 2012).