A new life entered the lands conquered by Alexander. Human intercourse
was increased and quickened to a degree not before known. Commercial
enterprise now found open roads between the Aegean and India; the new
Greek cities made stations in what had been for the earlier Greek
traders unknown lands; an immense quantity of precious metal had been
put into circulation which the Persian kings had kept locked up in their
treasuries (cf. Athen, vi. 231 e). At the same time Alexander himself
made it a principal concern to win fresh geographical knowledge, to
open new ways. The voyage of Nearchus from the Indus to the Euphrates
was intended to link India by a waterway with the Mediterranean lands.
So too Heraclides was sent to explore the Caspian; the survey, and
possible circumnavigation, of the Arabian coasts was the last enterprise
which occupied Alexander. The improvement of waterways in the interior
of the empire was not neglected, the Babylonian canal system was
repaired, the obstructions in the Tigris removed. A canal was attempted
across the Mimas promontory (Plin. _N.H._ v. 116). The reports of the
[Greek: Bematistai], Baeton and Diognetus, who accompanied the march of
Alexander's army, gave an exacter knowledge of the geographical
conformation of the empire, and were accessible for later investigators
(Susemihl, _Gesch. d. griech. Litt._, I. p. 544). Greek natural science
was enriched with a mass of new material from the observations of the
philosophers who went with Alexander through the strange lands (H.
Bretzl, _Botanische Forschungen d. Alexanderzuges_, 1903); whilst on the
other hand attempts were made to acclimatize the plants of the
motherland in the foreign soil (Theophr., _Hist. Plant._ iv. 4, 1).