196 Notes on the Evidence bearing But he adds that it will be safer to assume that the British Celts belonged to the later Bronze Age, as well as the Age of Iron. It is also necessary to remember that bronze would remain in use for many purposes after the introduction of iron, and that iron articles deposited in tumuli must have often perished while bronze ones have endured. More than two centuries after the voyage of Pytheas, Britain was visited by an eminent Greek named Posidonius, who gave some account of the people of Belerion or Cornwall and their tin-works. Posidonius is supposed to be the authority of Diodorus Siculus for the statement that the people of Britain had mean habitations, made for the most part of rushes and sticks, and that their harvest consisted in cutting off the ears of corn and storing them in pits under- ground, some of the corn which had been longest stored being taken out each day for food. As Pytheas confined his explor- ations to Eastern Britain, it is net surprising that he found a more advanced civilisation there, where there was constant intercourse with the Continent, than Posidonius did, two centuries later, in parts of the west little visited by merchants. Posidonius, however, remarks that the inhabitants of Belerium are very fond of strangers, and, from their intercourse with foreign merchants, are civilised in their manner of life. But, of course, the most primitive habits might exist a very few miles away from the commercial centres and routes, alike in the east and the west. In b.c. 55 and 54, some thirty or forty years after the visit of Posidonius, the two voyages of Julius Caesar to Britain took place; and we learn from his remarks on the reasons for visiting our island how little was known about it in Gaul.18 Caesar had been annoyed to find that in the wars of the Romans with the Gauls the latter were accustomed to receive help from Britain. He also found that merchants who had been in the habit of crossing over to Britain knew but the sea-coast and the parts opposite Gaul, and could tell him neither the size of the island, the numbers of its inhabitants, nor anything about their manners and customs, their modes 13 'De Bello Gallico,' Book iv., ch. 20.