124 ALEXANDER'S EASTERN EXPEDITION. [CHAP.
and the southern shores of the Caspian, and the northern shores
of the Persian Gulf, were explored. But the revelation of this
vast area was not, perhaps, in itself the most important result that
accrued to geographical study from these campaigns. An even
greater stimulus was communicated to it by the novel and striking
natural features with which the Greeks now became acquainted.
Novel AS- *n the course of their ^arches they passed over
pecta of desert plains and salt-steppes alternating with luxuri-
ature' antly fertile districts, and through snowy mountain-
chains exceeding in elevation anything that they had hitherto
conceived, among which the Hindu Kush reaches the height of
18,000 feet. The variety of configuration of the ground which
was thus presented to them, together with the differences of
climate and the unwonted size and strange appearance of the
vegetation, suggested innumerable points of comparison and
[contrast with the objects that they were familiar with in Europe.'
All these characteristics were carefully recorded by accurate
observers, for Alexander on this occasion had associated with
him so large a number of men of great attainments, that his
enterprise might claim the character of a scientific expedition.
Narratives Unfortunately not one of the narratives of these
oftheExpe- campaigns, which were composed by Aristobulus,
Onesicritus and others of his companions, has come
down to us, and we are compelled to trust for our knowledge of
them to histories written under the Roman empire—especially to
those of Arrian in Greek and Curtius in Latin, By these, how-
ever, we are to some extent indemnified for the loss of the original
authorities, because the facts which they contain are largely drawn
from their writings.
The expedition which Alexander so successfully executed was
The Expedi- not in realitv originated by him. It was designed
in the first instance ty his father» PlliliP of Macedon,
after he had broken the power of the independent
states of Greece, as a means of facilitating and consolidating his
hegemony, by uniting the Greeks in the common object of as-
sailing the traditional enemy of their country, the king of Persia,
He was making preparations • for this invasion, and a part of
tbe- requisite forces had been assembled,-when the project was