As Hoernes[115] says, it was this new trade which brought with it the close of the Neolithic period in northern Europe. But the change from the age of stone to that of bronze was anything but abrupt or sudden; in fact, it extended over more than 1,000 years. It was apparently not brought about by the invasion of a conquering race, though it was accompanied and followed by marked change and shifting of the population of central Europe. First we find a few copper ornaments and implements stealing into France and southern Europe. Then the metal becomes more abundant as people increase in wealth and can afford luxuries. Then bronze comes in from southeast and south, and very slowly north of the Alps. It meets the current of amber from the north. Thus the two most beautiful, precious, and desirable materials of the time have come together. Both are easy of transport. A trade which has long been preparing or proceeding on a small scale expands rapidly, perhaps suddenly, and ushers in a new period, which, after all, chiefly carries on or brings into prominence that which had begun or advanced during the preceding age. More interesting and, perhaps, more important than exchange of flint axes and amber is the spread of patterns, methods, influences; of new ideas and stimuli from mind to mind and people to people. A new implement, like the mace-heads and arm-rings, of which we have spoken; a new form of axe or dagger; the form and ornament of pottery; the building of dolmens or the spread of immigration with the accompanying change of cult and thought--all these brought not only economic improvement but growth of mind. Sophus Müller, and Montelius in a less degree, may have been somewhat extreme in their emphasis on the importance of oriental and Mediterranean influences and leadership, but their main thesis was correct.[116] Civilization and culture were far older in the Orient than in Europe, and far more advanced south than north of the Alps. These were the centres of radiation of ideas and stimuli as well as patterns, inventions, and discoveries.