ome difference of opinion; while in general they
denied the existence of human beings beyond the limits of their
Oecumene, or Inhabited World, this denial did not necessarily involve
disbelief in the globular figure of the earth.[454] The views of the
great mass of people, and of the more ignorant of the clergy, down to
the time of Columbus, were probably well represented in the book of
Cosmas Indicopleustes already cited.[455] Nevertheless among the more
enlightened clergy the views of the ancient astronomers were never quite
forgotten, and in the great revival of intellectual life in the
thirteenth century the doctrine of the earth's sphericity was again
brought prominently into the foreground. We find Dante basing upon it
the cosmical theory elaborated in his immortal poem.[456] In 1267 Roger
Bacon--stimulated, no doubt, by the reports of the ocean east of
Cathay--collected passages from ancient writers to prove that the
distance from Spain to the eastern shores of Asia could not be very
great. Bacon's argument and citations were copied in an extremely
curious book, the "Imago Mundi," published in 1410 by the Cardinal
Pierre d'Ailly, Bishop of Cambrai, better known by the Latinized form of
his name as Petrus Alliacus. This treatise, which throughout the
fifteenth century enjoyed a great reputation, was a favourite book with
Columbus, and his copy of it, covered with marginal annotations in his
own handwriting, is still preserved among the priceless treasures of the
Biblioteca Colombina.[457] He found in it strong confirmation of his
views, and it is not impossible that the reading of it may have first
put such ideas into his head. Such a point, however, can hardly be
determined. As I have already observed, these ideas were in the air.
What Columbus did was not to originate them, but to incarnate them in
facts and breathe into them the breath of life. It was one thing to
suggest, as a theoretical possibility, that Cathay might be reached by
sailing westward; and it was quite another thing to prove that the
enterprise was feasible with the ships and instruments then at command.

[Footnote 453: [Greek: Hoi de hemeteroi] [i. e. the Stoics]
[Greek: kai apo mathematon pantes, kai hoi pleious ton apo tou
Sokratikou didaskaleiou sphairikon einai to schema tes ges
diebebaiosanto.] Cleomedes, i. 8; cf. Lucretius, _De Rerum
Nat._, i. 1052-1082; Stobaeus, _Eclog._ i. 19; Plutarch, _De