He associated with various navigators, and he noted down all he heard. It was said by some that islands had been seen far away to the west when they had been driven in that direction. Whatever credit might have been given to these reports by Columbus, he had far stronger reasons for believing that, by sailing across the ocean to the west, he should reach land. He was of opinion that about one-third of the circumference of the earth was unknown and unexplored. A great portion of this might be filled up by the eastern regions of Asia, while the tract of water intervening between these countries might be less than at first supposed. In the thirteenth and fourteenth centuries, two great travellers, Marco Polo and Sir John Mandeville, journeyed eastward over a large portion of Asia, and had given vivid descriptions of the magnificence of its cities and scenery. Marco Polo especially had described two large islands, Ontilla and Cipango, the latter undoubtedly Japan, which it was expected would be the first reached by a navigator sailing westward. A Portuguese pilot, Martin Vicenti, after sailing four hundred and fifty-two leagues to the west of Cape Saint Vincent, had found a piece of carved wood evidently laboured with an iron instrument, and as probably the wind had drifted it from the west, it might have come from some unknown land in that direction. A brother-in-law of Columbus had likewise found a similar piece of wood drifted from the same quarter. Reeds of enormous size, such as were described by Ptolemy to grow in India, had been picked up, and trunks of huge pine-trees had been driven on the shores of the Azores, such as did not grow on any of those islands. The bodies of two dead men, whose features differed from those of any known race of people, had been cast on the island of Flores. There were islands, it was rumoured, still farther west than those visited, and a mariner sailing from Port Saint Mary to Ireland asserted that he had seen land to the west, which the ship's company took to be some extreme point of Tartary. These facts being made known to Columbus, served to strengthen his opinion. The success indeed of his undertaking depended greatly on two happy errors: the imaginary extent of Asia to the east, and the supposed smallness of the earth. A deep religious sentiment mingled with his meditations. He looked upon himself as chosen by Heaven for the accomplishment of its purposes, that the ends of the earth might be brought together, and all nations and tongues united under the banner of the Redeemer. The enthusiastic nature of his conceptions gave an elevation to his spirit, and dignity and eloquence to his whole demeanour. He never spoke in doubt or hesitation, but with as much certainty as if his eyes had beheld the promised land.