X.] GENERAL REMARKS ON THE SUBJECT. 215
being, as far as one may conjecture, the great superiority in size
of the external Ocean to our sea: while the channel at Abydos is
more convenient than that at the Pillars of Heracles. For the
former being lined on both sides by human habitations is of the
nature of a gate admitting mutual intercourse, sometimes being
bridged over by those who determine to cross on foot, and at all
times admitting a passage by sea. But the channel at the Pillars
of Heracles is seldom used, and by very few persons, owing to
the lack of intercourse between the tribes inhabiting those remote
parts of Libya and Europe, and owing to the scantiness of our
knowledge of the external Ocean1."
The combination of realism with reflective observation, which
we thus meet with in Polybius' treatment of geography in con-
nexion with history, makes us feel that we have entered on a new
and peculiarly useful application of the subject; and this, as we
shall presently see, was afterwards carried out on a larger scale
by Strabo, whose views were greatly influenced by those of his
predecessor.
1 Polyb., 16. 29.