Again, there is land that yields no fruit if sown, and yet, when quarried, feeds many times the number it could support if it grew corn. And recollect, there is silver in the soil, the gift, beyond doubt, of divine providence: at any rate, many as are the states near to her by land and sea, into none of them does even a thin vein of silver ore extend. One might reasonably suppose that the city lies at the centre of Greece, nay of the whole inhabited world. For the further we go from her, the more intense is the heat or cold we meet with; and every traveller who would cross from one to the other end of Greece passes Athens as the centre of a circle, whether he goes by water or by road.