Cliap. 10.] ACCOTOT OF COtTNTEIES, ETC. 413 
either that its waters are driven back by the Etesian winds \ 
which are blowing at this season of the year from an oppo- 
site direction, and that the sea which lies beyond is driven 
into the mouths of the river ; or else that its waters are 
swollen by the summer rains of ^thiopia^, wnich fall from 
the clouds conveyed thither by the Etesian winds from 
other parts of the earth. Timaeus the mathematician has 
alleged a reason of an occult nature : he says that the source 
of the river is known by the name of Phiala, and that the 
stream buries itself in channels underground, where it sends 
forth vapours generated by the heat among the steaming 
rocks amid which it conceals itself; but that, during the days 
of the inundation, in consequence of the sun approaching 
nearer to the earth, the waters are drawn forth by the 
influence of his heat, and on being thus exposed to the 
air, overflow; after which, in order that it may not be 
utterly dried up, the stream hides itself once more. He 
says that this takes place at the rising of the Dog- Star, 
when the sun enters the sign of Leo, and stands in a vertical 
position over the source of the river, at which time at 
that spot there is no shadow thrown. Most authors, however, 
are of opinion, on the contrary, that the river flows in greater 
volume when the sun takes his departure for the north, which 
he does when he enters the signs of Cancer and Leo, because 
its waters then are not dried up to so great an extent ; while 
on the other hand, when he returns towards the south pole and 
re-enters Capricorn, its waters are absorbed by the heat, 
and consequently flow in less abundance. If there is 
any one inclined to be of opinion, with Timaeus, that the 
waters of the river may be drawn out of the earth by the 
heat, it will be as well for him to bear in mind the fact, that 
the absence of shadow is a phsenomenon which lasts conti- 
nuously^ in these regions. 
^ The Etesians are periodical winds, which blow steadily from one 
quarter for forty days each year, during the season of the Dog-days, 
The opinion here stated was that promulgated by Thales the philosopher. 
Seneca refutes it in B. iv. c. 2. of his Qusest. Nat. 
2 This was the opinion of Democritus of Abdera, and of Agathar- 
chidas of Cnidos. It is combated by Diodorus Siculus, B. i., but it is 
the opinion most generally received at the present day. See the disqui- 
sition on the subject introduced in the Ninth book of Lucan's Pharsaha. 
3 And that the high tide or inundation would be consequently con* 
tinuous as well. 
