The achievements of the Greeks and Romans were still more limited. A certain Colaeus visited Gades towards the middle of the seventh century B.C., and was, according to Herodotus, the first Greek who passed outside of the columns of Hercules. His example could not have been widely followed, for we find Pindar and his successors referring to the Pillars as the limit of navigation. In 600 B.C., Massilia was founded, and soon became a rival of Carthage in the western Mediterranean. In the fourth century we have evidence of an attempt to search out the secrets of the ocean after the manner of Hanno and Himilko. In that century, Pytheas made his famous voyage to the lands of tin and amber, discovering the still mysterious Thule; while at the same time his countryman Euthymenes sailed southward to the Senegal. With these exceptions we hear of no Grecian or Roman explorations in the Atlantic, and meet with no indication that they were aware of any other lands beyond the sea than the Fortunate Isles or the Hesperides of the early poets.[311] About 80 B.C., Sertorius, being for a time driven from Spain by the forces of Sulla, fell in, when on an expedition to Baetica, with certain sailors who had just returned from the “Atlantic islands,” which they described as two in number, distant 10,000 stadia from Africa, and enjoying a wonderful climate. The account in Plutarch is quite consistent with a previous knowledge of the islands, even on the part of Sertorius. Be this as it may, the glowing praises of the eye-witnesses so impressed him that only the unwillingness of his followers prevented his taking refuge there. Within the next few years, the Canaries, at least, became well known as the _Fortunatae Insulae_; but when Horace, in the dark days of civil war, urged his countrymen to seek a new home across the waves, it was apparently the islands of Sertorius that he had in mind, regarding them as unknown to other peoples.[312]