When Christianity sprang into existence Eusebius, St. John Chrysostom, and Cosmos evolved a complete description of the earth. They considered the earth as a parallelogram, flat, and surrounded by four seas, as a kind of house, with heaven as its upper story and the earth as its ground floor. To the north of the earth was a great mountain; at night the sun was pushed into a pit and pulled out again in the morning, with heaven as a loft and hell as a cellar. In the Atlantic Ocean, at some unknown distance from Europe, was one of the openings into hell, into which a ship sailing to this point, would tumble. The terror of this conception was one of the chief obstacles of the great voyage of Columbus. Luther, Melanchthon, Calvin, and Zwingli held to the opinion that a great firmament, or floor, separated the heavens from the earth; that above it were the waters and angels, and below it, the earth and man. During the time that the sphericity of the earth was still undecided, another question arose that was considered of far greater importance, namely, the conception of the antipodes and the problem of deciding whether human beings existed on the earth's opposite side. It was Lactantius who asked, "Is there any one so senseless as to believe that there are men whose footsteps are higher than their heads? That the crops and trees grow downward? That the rains and snow and hail fall upwards toward the earth? I am at a loss as to what to say of those, who, when they have once erred, steadily persevere in their folly, and defend one vain thing by another." St. Augustine insisted that men could not be allowed by the Almighty to live there, since, if they did, they could not see Christ at His second coming, descending through the air. In the eighth century, a Bishop Virgil of Salzburg dared to assert that there were men living in the antipodes. He was strongly attacked by St. Boniface of Germany, who appealed to Pope Zachary for a decision. The Pope, as the infallible teacher of Christendom, made the following response: He declared it, "Perverse, iniquitous, and against Virgil's soul." And again another infallible statement by the infallible Pope Zachary became a doctrine of the Church. In Italy, in 1316, Peter of Abano, famous as a physician, promulgated the opposite view to that of the Church, for which he was persecuted by the Inquisition, and barely escaped with his life. In 1327, Cecco d'Ascoli, an astronomer, was burned alive at Florence for daring to assert that men lived in the antipodes.