J. Preuss, Biblical and Talmudic Medicine, trans. F. Rosner (1978) 19–20; S. Kottek, “Alexandrian medicine
in the Talmudic corpus,” Koroth 12 (1996–1997) 85–87.
Annette Yoshiko Reed
Theodosios (Empir.) (150 – 210 CE)
Physician, mentioned by G together with S and M as an
exponent of the Empiricist “school” (Med. Exp. 29), and included in the list of Empiri-
cists contained in the MS Hauniensis Lat. 1653 f.73 (following Me ̄nodotos and T
L). He is probably to be identified with the skeptic philosopher to whom
D L (9.70) ascribes the opinion that the Skepticism cannot be called
“Pyrrhonism,” and a work entitled Skeptical Chapters (also in Souda Theta-132, mentioning
also the title Comment on Outlines of Theodas, and mistakenly identified with T
B). If his name goes back to the original version of Gale ̄n’s juvenile treatise,
Theodosios was already active by the mid 2nd c. CE.
Ed.: Deichgräber (1930) 219 (fragments).
RE 5A.2 (1934) 1929–30 (#3), K. von Fritz; KP 5.699 (#1), H. Dörrie; NP 12/1.339–40 (#2), M. Frede.
Fabio Stok
Theodosios (of Bithunia) (200 – 50 BCE)
Mathematician, wrote three extant treatises on mathematical astronomy and a lost com-
mentary on A’ Method, which establishes the only sure terminus post for his career.
S lists him (together with his unnamed sons) as a noteworthy Bithunian mathemat-
ician, and V 9.8.1 as the inventor of a kind of sundial. An entry on Theodosios in
the Souda, Theta-142, which ascribes philosophical and poetic works to him and states that
he came from Tripolis, apparently confuses him with two other homonymous men.
The Spherics, in three books, was much studied in later antiquity (at least from the time of
P, who commented on it in Book 6 of his Collection). It is an elementary work on
spherical geometry, with applications to astronomical problems that though obvious are
never mentioned in the text; Theodosios’ contribution was primarily to edit and organize
material already known in the 3rd c. BCE if not earlier. Underlying the work are the con-
ventional assumptions of contemporary astronomy, that the Earth and heavens are both
spherical and concentric and that the Earth has a point-like magnitude in relation to the
celestial sphere. The most advanced theorems demonstrate inequalities subsisting among
the arcs of the horizon or the celestial equator corresponding to equal rising arcs of the
ecliptic circle for observers situated either on or away from the terrestrial equator; for
example these theorems allow comparison of the length of time required for successive
signs of the zodiac to cross one’s horizon. The treatise lacks theorems on configurations of
great circle arcs (“M’ Theorem”) by which P derives numerical values for
quantities in spherical astronomy in Almagest Books 1–2.
On Habitations is a collection of 12 theorems concerning risings and settings of stars and
length of daylight for different locations on the Earth; since most of the situations discussed
are either close to the equator or near the poles, the book is clearly an intellectual exercise,
not related to real observing conditions. The two books of On Days and Nights are similarly
impractical, dealing with such questions as criteria for having day and night exactly equal at
an equinox, taking into account the Sun’s small movement along the ecliptic during the
day in question.
THEODOSIOS (OF BITHUNIA)