The theologians generally rejected the idea of sphericity. There were, however, some very notable exceptions. The doctrine was positively taught by Saint Isadore of Seville, and was somewhat elaborately set forth by the Venerable Bede. Of still more importance was the unquestioning acceptance of this doctrine by that great protagonist of the faith, Saint Thomas Aquinas. Albertus Magnus, Roger Bacon, and Dante seem also, in a more or less definite form, to have accepted the same doctrine. In any account, however brief, of the early years of Columbus, a statement should also be made concerning some of the explorers who had performed an important part in pushing out the boundaries of knowledge. One of the most remarkable of these was John de Mandeville. It is very properly the fashion to regard this audacious romancer as one of the most unscrupulous of all explorers. It is certain that he did not see a quarter or perhaps even a tenth part of the things which he affects to describe. But in spite of all these characteristics, there is one passage in the book that can hardly fail to have made a deep impression on the mind of Columbus. In this remarkable passage the author relates, in the quaint language of the time, how he himself came to the conclusion that the earth was a sphere. His words are,-- “In the north the south lodestar is not seen; and in the south, the north is not seen.... By which say you certainly that men may environ all the earth, as well under as above, and turn again to his country, and always find men as well as in this country.... For ye witten well that they that turn toward the antarctic, be straight feet against feet of them that dwell under the transmontayne, as well as we and they that dwell under us be feet against feet.” Of still more importance in shaping directly or indirectly the opinions of Columbus was the great work of Marco Polo. This Venetian traveller, after spending many years in China and Japan, and having the best of opportunities for observation, published the great work on which his reputation as a traveller and writer is founded. He not only described with considerable minuteness the countries which he visited, but he pictured, though with gross exaggerations, the great wealth of many of the eastern cities. Columbus supposed that these regions, still in the hands of infidels, could be reached by sailing westward across the Atlantic.