, Strabo assures us, accords with the most accurate observations
"both ancient and modern." These observations seemed to show that it is
not possible to live in the region close to the equator, and that, on
the other hand, the cold temperature sharply limits the habitability of
the globe towards the north. All the civilization of antiquity clustered
about the Mediterranean, or extended off towards the east at about the
same latitude. Hence geographers came to think of the habitable globe as
having the somewhat lenticular shape which a crude map of these regions
suggests. We have already had occasion to see that at an earlier day
Anaxagoras was perhaps influenced in his conception of the shape of the
earth by this idea, and the constant references of Strabo impress upon
us the thought that this long, relatively narrow area of the earth's
surface is the only one which can be conceived of as habitable.

Strabo had much to tell us concerning zones, which, following
Posidonius, he believes to have been first described by Parmenides. We
may note, however, that other traditions assert that both Thales
and Pythagoras had divided the earth into zones. The number of zones
accepted by Strabo is five, and he criticises Polybius for making
the number six. The five zones accepted by Strabo are as follows: the
uninhabitable torrid zone lying in the region of the equator; a zone
on either side of this extending to the tropic; and then the temperate
zones extending in either direction from the tropic to the arctic
regions. There seems to have been a good deal of dispute among the
scholars of the time as to the exact arrangement of these zones, but the
general idea that the north-temperate zone is the part of the earth
with which the geographer deals seemed clearly established. That the
south-temperate zone would also present a habitable area is an idea that
is sometimes suggested, though seldom or never distinctly expressed. It
is probable that different opinions were held as to this, and no direct
evidence being available, a cautiously scientific geographer like Strabo
would naturally avoid the expression of an opinion regarding it. Indeed,
his own words leave us somewhat in doubt as to the precise character of
his notion regarding the zones. Perhaps we shall do best to quote them:

"Let the earth be supposed to consist of five zones. (1) The equatorial
circle described around it. (2) Another parallel to this, and defining
the frigid z