COSMOS, VOL. II - World eBook Library

INFLUENCE OF THE PTOLEMAIC EPOCH. 543
inculcated in the Alexandrian Museum;* and this science
comprehended in the advanced stages of its development pure
mathematics, mechanics, and astronomy. In Plato's high
appreciation of mathematical development of thought, as well
as in Aristotle's morphological views which embraced all
organisms, we discover the germs of the subsequent advances
of physical science. They became the guiding stars which led
the human mind through the bewildering fanaticism of the
dark ages, and prevented the utter destruction of a sound and
scientific manifestation of mental vigour.
The mathematician and astronomer, Eratosthenes of Gyrene,
the most celebrated of the Alexandrian librarians, employed
the materials at his command to compose a system of universal
geography. He freed geography from mythical legends, and,
although himself occupied with chronology and history,
separated geographical descriptions from that admixture of
historical elements with which it had previously been not un-
gracefully embodied. The absence of these elements was,
however, satisfactorily compensated for by the introduction of
mathematical considerations on the articulation and expansion
of continents ; by geognostic conjectures regarding the connection
of mountain chains, the action of clouds, and the former
submersion of lands, which still bear all the traces of having
constituted a dried portion of the sea's bottom. Favourable
to the oceanic sluice-theory of Strabo of Lanrpsacus, the Alexandrian
librarian was led, by the belief of the former swelling
of the Euxine, the penetration of the Dardanelles, and the
consequent opening of the Pillars of Hercules, to an important
investigation of the problem of the equal level of the whole
"
external sea f surrounding all continents." An additional
proof of this philosopher's power of generalising views is
afforded by his assertions that the whole continent of Asia is
traversed by a continually connected mountain chain, running
*
Fries, Geschichte der Philosophie, bd. ii. s. 5; and the same
author's Lehrbuch der Naturlehre, th. i. s. 42. Compare also the considerations
on the influence which Plato exercised on the foundation of the
experimental Sciences by the application of mathematics, in Brandis,
Geschichte der griechiscli-romisclien Philosophie, th. ii. abth. i. s. 276.
t On the physical and geognostical opinions of Eratosthenes, see
Strabo, lib. i. pp. 49-56, lib. ii. p. 108.