Portugal was prosecuting modern discovery with great enthusiasm, seeking a route to India by the coast of Africa; Columbus's genius conceived the bold idea of seeking India across the Atlantic. He set it down that the earth was a terraqueous globe, which might be travelled round. The circumference he divided into twenty-four hours. Of these he imagined that fifteen hours had been known to the ancients; the Portguese had advanced the western frontier one hour more by the discovery of the Azores and the Cape de Verde Islands; still, about eight hours remained to be explored. This space he imagined to be occupied in great measure by the eastern regions of Asia. A navigator, therefore, pursuing a direct course from east to west, must arrive at Asia or discover intervening land. The work of Marco Polo is the key to many of the ideas of Columbus. The territories of the Great Khan were the object of his search in all his voyages. Much of the success of his enterprise rested on two happy errors; the imaginary extent of Asia to the east, and the supposed smallness of the earth. Without these errors he would hardly have ventured into the immeasurable waste of waters of the Atlantic. A deep religious sentiment mingled with his thoughts; he looked upon himself as chosen from among men, and he read of his discovery as foretold in Holy Writ. Navigation was still too imperfect for such an undertaking; mariners rarely ventured far out of sight of land. But knowledge was advancing, and the astrolabe, which has been modified into the modern quadrant, was being applied to navigation. This was the one thing wanting to free the mariner from his long bondage to the land. Columbus now laid his great project before the King of Portugal, but without success. Greatly disappointed, he sailed to Spain, hoping to receive the patronage of Ferdinand and Isabella. It was many months before he could even obtain a hearing; his means were exhausted, and he had to contend against ridicule and scorn, but the royal audience was at length obtained. Ferdinand assembled learned astronomers and cosmographers to hold a conference with Columbus. They assailed him with citations from the Bible. One objection advanced was, that should a ship ever succeed in reaching India, she could never come back, for the rotundity of the globe would present a mountain, up which it would be impossible to sail. Finally, after five years, the junta condemned the scheme as vain and impossible.