1 The Birth of Science - MSRI

11.1 The Early Renaissances 291
Pisa, certain authors have even credited him with being the first to contradict
Aristotelian mechanics. 6
Next came what has been called the Islamic Renaissance. Interest in science
started in Islam during the eighth century, following the Abbasid
revolution, under Caliphs al-Man. sūr and Hārūn ar-Rashīd, and reached
its heyday in the ninth century, under Caliph al-Ma’mūn. 7 It was then that
extant Arabic translations of Hellenistic scientific treatises started being
made. A copy of Euclid’s Elements was requested for this purpose from
the Byzantine Emperor by the Caliph (either al-Man. sūr or al-Ma’mūn, depending
on the source). Byzantium, too, experienced around that time a
renewal in scientific interest, perhaps under the stimulus of the Islamic
revival. Among the numerous works published in Byzantium during the
ninth century were many editions of scientific texts: we have mentioned
(page 46) one containing Archimedes’ works, based on that of Isidore.
Islamic scientists — to whom we are indebted in a fundamental way
for the survival of science — devoted themselves above all to the exegesis
of scientific works from the imperial period; they regarded Ptolemy and
Galen as the highest authorities in astronomy and medicine, respectively.
Optics was recovered primarily thanks to ibn Sahl, whose one extant
work dates from around 893, and ibn al-Haytham, also known as Alhazen
(ca. 965 to ca. 1039). Both wrote about mirrors of different shapes and also
lenses. Alhazen’s Optics, after treating other subjects in close emulation of page 361
Ptolemy’s homonymous work, discusses the theory of spherical lenses. 8 It
was Alhazen who, based on the observation that light is not emitted but
only received by eye, banished the notion of a “visual ray” from Islamic
optics. Whereas Alhazen, like Ptolemy, did not apply the theory of conics
to optics, ibn Sahl before him had done so systematically, and considered
not only parabolic and elliptic mirrors but even plane-convex and biconvex
lenses bounded by hyperboloids. 9
Interest in Hellenistic science is simultaneous with the development of
several industries: textiles, paper, metals, ships. Even “alchemy” is closely
connected with productive processes: arrays of stills, for example, were
6 See the articles in [Sorabji]. We will return to Philoponus’ knowledge of mechanics on page 308.
7 For extensive coverage of the history of Arabic science, see [Rashed: HAS].
8 Alhazen, Kitāb al-manāz. ir (Book of optics), VII = [Rashed: GD], pp. 83–110. For the relationhsip
between Alhazen and Ptolemy in their exposition of earlier topics, see [Smith]. Recall (note 38
on page 56) that we lack parts of Ptolemy’s Optics, including everything after the treatment of
refraction through plane and cylindrical surfaces (the preceding topic being reflection in plane and
spherical mirrors).
9 Ibn Sahl, Kitāb al-h. arrāqāt (Book of burning instruments). This work, written between 982 and 984,
was recognized by R. Rashed in a manuscript in Teheran and published in [Rashed: GD]. See also
[Rashed: PA].
Revision: 1.11 Date: 2003/01/06 07:48:20