Science, though its matter was attractive enough to the practical Roman, was at a standstill. So far as it existed it was Greek. The Greeks had done almost all that could be done by sheer brain-power and acumen. They could hardly proceed further without those finer instruments which we possess, but which they did not. Though they knew of certain magnifying glasses, they had no real telescopes or microscopes, no mariner's compass or chronometers, no very delicate balances. They possessed a magnificent thinking apparatus and put it to admirable use. The modern scientist has generally nothing but admiration for their keen insight, and for the brilliant hypotheses which they invented and which were frequently but unverified anticipations or partial anticipations of theories now in vogue. Where they stopped short was at experiment in test of hypothesis. Of all exploits of pure thinking in the domain of science perhaps the greatest has been the conception that the earth, instead of being a flat disk, is a sphere. This theory was held before the age of Nero by ancient astronomers and geographers, who had derived the notion partly from the eclipses of the moon--of which they well understood the cause--and partly from the rising of objects above the horizon. They understood also that in a sphere there was gravitation to the centre, and were able so to comprehend the level surface of water on the globe. The geographer Strabo, more than a generation before our chosen date, readily conceives that, if one sailed straight westward out of the Mediterranean through the Straits of Gibraltar, he would ultimately come back round the world by way of the East--that is to say, by India. It was not left for Columbus to invent that doctrine. It is true that in calculating the circumference of the earth they had made it as much as one-seventh too large, but the wonder is that they came so near as they did. In regard to the distance of the moon they were not more than 1/12th from the modern estimate. The possibility of error in dealing with the sun was much greater, and their 51,000,000 miles is little more than half of what it should have been. Exactly how far this doctrine of the sphericity of the earth was popularly entertained we cannot tell; it was probably almost confined to those directly interested in the question. A theory, anticipating Galileo, that it is the earth which moves round the sun, had been mooted, but certainly had very little currency. Nor was speculation confined to such astronomical conclusions. In the region of physical geography rational attempts were made to account for various phenomena, such as the existence of deltas or the risings of the Nile, or the appearance of sea-shells high on dry land. Strabo, in dealing with the Black Sea, has his theories of the elevation or subsidence of land. He also suggests previous volcanic conditions of certain districts which had been quiescent from before the memory or tradition of the inhabitants.