That the earth is an island, Strabo considers to be proved by the testimony of our senses. For wherever men have reached to the extremities of the earth they have found the sea, and for regions where this has not been verified it is established by reasoning. Those who have retraced their steps have not done so because their passage was barred by any continent, but because their supplies have run short, and they were afraid of the solitude; the water always ran freely in front of them. It is extraordinary that Strabo and the astronomers of that age, who recognised so clearly the sphericity of the earth and the real insignificance of mountains, should yet have supposed the stars to have played so humble a part, but so it was; and we find Strabo arguing in what we may call quite the contrary direction. He says, "the larger the mass of water that is spread round the earth, so much more easy is it to conceive how the vapours arising from it are sufficient to nourish the heavenly bodies." [Illustration: FIG. 33.--THE EARTH OF THE LATER GREEKS.] Among the Latin cosmographers we may here cite one who flourished in the first century after Christ, Pomponius Mela, who wrote a treatise, called _De Situ Orbis_. From whatever source, whether traditional or otherwise, he arrived at the conclusion, he divided the earth into two continents, our own and that of the Antichthones, which reached to our antipodes. This map was in use till the time of Christopher Columbus, who modified it in the matter of the position of this second continent, which till then remained a matter of mystery. [Illustration: FIG. 34.--POMPONIUS MELA'S COSMOGRAPHY.] Of those who in ancient times added to the knowledge then possessed of cosmography, we should not omit to mention the name of Pytheas, of Marseilles, who flourished in the fourth century before our era. His chief observations, however, were not so closely related to geography as to the relation of the earth with the heavenly bodies. By the observation of the gnomon at mid-day on the day of the solstice he determined the obliquity of the ecliptic in his epoch. By the observation of the height of the pole, he discovered that in his time it was not marked by any star, but formed a quadrilateral with three neighbouring stars, [Greek: b] of the little Bear and [Greek: k] and [Greek: a] of the Dragon. CHAPTER X. COSMOGRAPHY AND GEOGRAPHY OF THE CHURCH.