Some alleged, that since so many skilful sailors, during the many thousand years which had elapsed from the creation of the world, had not acquired any knowledge whatever of these countries, it was not at all probable that he should know more of the matter than all who had gone before or who now existed. Others, pretending to ground their opinion upon cosmographical arguments, said that the world was of such prodigious size that they questioned if it were possible to sail in three years to the eastern extremity of India, whither he proposed to go; and they endeavoured to confirm this opinion by the authority of Seneca, who says in one of his works, "That many wise men disagreed about whether the ocean were of infinite extent, and doubted whether it were navigable, and whether habitable lands existed on its other side; and, even if so, whether it were possible to go to these." They added, that only a small proportion of this terraqueous globe, which had remained in our hemisphere above the water, was habitable; and that all the rest was sea, which was not sussceptible of being navigated, except near the coasts and rivers; and that wise men denied the possibility of sailing from the coast of Spain to the farthest parts of the west. Others argued nearly in the same manner as had been formerly done by the Portuguese in regard to the navigation along the western coast of Africa: That if any one should sail due westwards, as proposed by the admiral, it would certainly be impossible to return again to Spain; because whoever should sail beyond the hemisphere which was known to Ptolemy, would then go downwards upon the rotundity of the globe, and then it would be impossible to sail up again on their return, which would necessarily be to climb up hill, and which no ship could accomplish even with the stiffest gale. Although the admiral gave perfectly valid answers to all these objections; yet, such was the ignorance of these people, that the more his reasons were powerful and conclusive so much the less were they understood: For when people have grown old in prejudices and false notions of philosophy and mathematics, these get such firm hold of the mind that true and just principles are utterly unintelligible.