Maximilian Otto Bismarck Caspari and Ernest Arthur Gardner, 1911 Encyclopædia Britannica, Volume 26… (1911)
“ The entire plain was well adapted for pasturage and corn-growing, but was liable to floods owing to the lack of free outlets for its water-courses. Hence the regulation of the zerethra or subterranean conduits which drained away the overflow southward was a matter of vital importance both to Tegea and to Mantineia, and a cause of frequent quarrels. By its vicinity to the watersheds of the Eurotas and Alpheus, and its command over the main roads from Laconia to Argos and the Isthmus, Tegea likewise was brought into conflict with Sparta. ”
