Severus Sebokht
[Sebokt, Sebukht, Seboht]
John M. McMahon
Born Nisibis, (Syria),
circa 575
Died Kennesrin (also
called Qinnesrin or Qenneshrê), (Syria), 666/667
Severus
Sebokht was one of the leading figures of ecclesiastical, philosophical,
and scientific culture of late antique Syria, although little definitive
information is known about his life. Born in Persian territory at Nisibis,
he left his teaching post in its famous school in 612 after a doctrinal
dispute among the Nestorians. Later consecrated a bishop, he pursued a career
in the Syrian Monophysite church within Byzantine jurisdiction, residing
as a monk at the monastery at Kennesrin on the west bank of the Euphrates,
one of the chief seats of Greek learning in western Syria. He continued
to write until at least 665.
Like
many of his contemporaries, Severus was bicultural, partaking of the Byzantine
Greek influence on western Syrian intellectual circles while fully immersed
in his own Syrian cultural milieu. He does, however, criticize the contemporary
Greek tendency to assume intellectual superiority and asserts his own capabilities
as a native Syrian, raising a strong polemical voice against the cultural
hegemony of the Greek‐speaking world over that of provincials. A leading
figure in the teaching and commentary tradition of Aristotelian philosophy,
especially in logic and syllogisms, Severus produced a Discourse on Syllogisms
in Prior Analytics (638) and wrote commentaries on other philosophical
texts. He translated Paul the Persian's commentary on Aristotle's
De interpretatione into Syriac. Severus also played an important
role in the transmission of Indian intellectual concepts into Syria and
ultimately into the Islamic world. In one famous passage, he praises the
Hindu decimal concept and mentions for the first time in the Greek east
the nine numerical symbols used in India.
It
was in astronomical matters, however, that Severus was preeminent. Syrian
astronomy was predominantly Ptolemaic, and Severus himself stands as an
important figure in passing on Greek astronomical knowledge to Syrian scholars
and thence to Islamic civilization. He was familiar with Ptolemy's
Handy Tables, and there is some indication that he translated the
Almagest into Syriac; in any case, he most certainly taught it in
the school of Nisibis and then later in western Syria. Similarly, Severus
was an important link in the transmission of the Greek tradition of the
astrolabe to the east. In several passages in his astronomical works, he
positions himself firmly on the side of scientific methodology and opposes
speculative astrology.
Severus
made two major contributions to astronomy. The first, a Treatise on the
Astrolabe, is based on a lost work by Theon
of Alexandria, the contents of which Severus preserved in his own
work. Written in 660, it is in two parts. The first is a general description,
including information about the following basic elements of the instrument
– the disks, the spider, the diopter, the zones, and related aspects of
the physical and mechanical parts. Instructions on its actual use comprise
the second part of the work, divided into 25 chapters, of which two (12,
20) are missing. These chapters cover all the applications of the instrument
– determining the hour of the day and night (1–3), finding the longitude
of the Sun, Moon, and planets and the latitude of the Moon (4–6), checking
the instrument (7–8), ascertaining the rising and setting times of various
signs (9–10, 25) and the length of daylight during the course of the year
(11), locating the geographical longitude and latitude of cities and establishing
the differences of local noons (13–15), fixing the ascensions on the right
sphere (16), finding latitudes of the observer and of each climate (17–18),
estimating the longitude and latitude of stars and their first and last
visibility (19, 21), observing the ecliptic and the declination of the Sun
(22–23), and recognizing the five zones on the celestial and terrestrial
spheres (24).
Severus's
other astronomical work (generally entitled Treatise on the Constellations ) was written in 660, subsequent to that
on the astrolabe. Eighteen original chapters are extant. The work begins
with five chapters forming a scientific critique of astrological and poetic
claims about the origins and significance of the constellations. In them,
Severus shows that the figures of the constellations are not arranged in
the heavens through natural means but rather are a result of human imagination.
Importantly, Chapter 4 features extracts from the Phaenomena of Aratus
concerning many of the constellations. The remaining 13 chapters (6–18)
are devoted to a scientific analysis of the heavens and the Earth. Here
Severus enumerates the 46 constellations and their noteworthy stars and
explains their various motions and their rising and settings. He also discusses
the celestial geography of the Milky Way and the ten “circles” of the heavens,
including the tropics, the equator, the meridian, the horizon, and the ecliptic.
Three chapters (14–16) examine extensively the seven climatic zones, their
location and extent, their relationship to the Sun, and the length of the
days and nights in each, the latter in accordance with Ptolemy's Handy
Tables. In the final two chapters, Severus treats the extent of the
Earth and the sky and considers the populated and uninhabited regions of
the Earth. In 665, Severus appended to this work nine additional chapters,
designed to answer a variety of astronomical, cosmological, and mathematical
questions posed by Basil of Cyprus, a visiting cleric. Included are treatments
of the conjunctions of planets and of various points about climatic zones,
the astrolabe, the determination of the date of Easter in April 665, and
the date of the birth of Christ. In other passages extant in the manuscripts,
Severus also writes on the phases of the Moon and on eclipses, in one case
explaining lunar eclipses scientifically to dispel the popular idea that
a dragon (Ataliâ) was responsible for such events.
Selected References
Brock,
Sebastian P. (1984). “From Antagonism to Assimilation:
Syriac Attitudes to Greek Learning.” In Syriac Perspectives on Late Antiquity.
Vol. 5, pp. 17–34, esp. 23–24, 28. London: Variorum Reprints. (For specialized
treatment of Severus and his contemporaries.)
Gunther, Robert T. (1932). The Astrolabes of the World.
Vol. 1, The Eastern Astrolabes. Oxford: University Press, pp. 82–103.
(For an English version of Treatise on the Astrolabe, from Nau's French.)
Moosa, Matti (ed. and trans.) (2000). The History of Syriac
Literature and Sciences. Pueblo, Colorado: Passeggiata Press, pp. 65,
108. (Originally published as I. Aphram Barsoum, Kitāb al‐Luʾluʾ
al‐manthūr fī taʾrīkh al‐ʿulūm
wa‐ʾl‐ādāb al‐Suryāniyya. Hims,
Syria, 1943). (Earlier treatments of Severus are now incorporated into this
work, which conveniently lists and briefly discusses all of Severus's works.)
Nau,
F. N. (1899). “Le traité sur l'astrolabe plan de Sévère Sabokt.” Journal
asiatique, 9th ser., 13:
56–101, 238–303. (For the Treatise on the Astrolabe.)
———.
(1910). “La cosmographie au VIIe siècle chez les Syriens.” Revue de l'Orient
chrétien 5, no. 18: 225–254. (Assesses Severus's contributions
and surveys the contents of Paris MS Syr. 346, three quarters of which is
made up of his works.)
———. (1910). “Notes
d'astronomie syrienne.” Journal asiatique, 10th ser., 16: 209–228,
esp. 219–224. (For Severus's explanation of lunar eclipses.)
———.
“Le traité sur les ‘Constellations' écrit, en 661 [sic], par Sévère
Sébokt, évêque de Qennesrin.” Revue de l'Orient chrétien 7, no. 27 (1929): 327–410; 8, no.
28 (1932): 85–100.
Neugebauer, Otto (1949). “The Early History of the Astrolabe.”
Isis 40: 240–256, esp. 242–245, 251–253. (For Severus's treatise on
the astrolabe; discusses Severus's sources and critiques earlier discussions.)
———. (1975). A
History of Ancient Mathematical Astronomy. 3 pts. New York: Springer‐Verlag,
pt. 1, pp. 7–8; pt. 2, pp. 877–878, 1041–1042. (For a brief treatment of the
relationship between Greek and Syrian astronomy and its transmission to the
Islamic World and Severus's treatise on the astrolabe.)
Pingree, David (1993). “The Greek Influence on Early Islamic
Mathematical Astronomy.” Journal of the American Oriental Society 93:
32–43, esp. 34–35.
——— (1994). “The Teaching
of the Almagest in Late Antiquity.” In The Sciences in Greco–Roman Society,
edited by Timothy D. Barnes, pp. 73–98, esp. 94–95. Edmonton: Academic Print
and Publishing.
Stautz, Burkhard (1997). Untersuchungen von mathematisch–astronomischen
Darstellungen auf mittelalterlichen Astrolabien islamischer und europäischer
Herkunft. Bassum: Verlag für Geschichte der Naturwissenschaften und der
Technik, pp. 38–39. (Gives a concise description of the physical appearance
of the instrument.)
Wright, W. (1966). A Short History of Syriac Literature.
Amsterdam: Philo Press, pp. 137–139.
Corrections/Additions