But the view that is opened up is still wider. The prehistoric times of the New World also exhibit a Neolithic stage, corresponding to that of Europe, as the basis of the further development of the ancient civilised lands of America. And where a higher civilisation did not develop autochthonously in America, European discoverers found the Neolithic civilisation still in active existence, as they did in the whole Australian world. Accordingly in these vast regions, which have never risen above the Stone Age of themselves, the same stage of civilisation which in the old civilised lands belongs to a grey, immemorial, prehistoric period, here stands in the broad light of historic times. The study of modern tribes in an age of stone throws many a ray of light on the conditions of the prehistoric Stone Age; and this study, on the other hand, shows us that the primitive conditions of civilisation of those tribes stand for a general stage of transition in the development of all mankind. [Sidenote: The Foundations of Society] The lake-dwelling stations, and the land settlements resembling them, prove of themselves how far the culture of the early inhabitants of Europe was advanced even in that ancient period which was formerly imagined to be scarcely raised above half-animal conditions. Such structures could not be erected unless men combined into large social communities, which is indeed indicated by the very fact of the number of dwellings that were crowded into a comparatively small space. For the first ramming-in of the pile-works a large number of men working together on a common plan was absolutely necessary. The same applies to the construction of the artificial islands, protected by pile-works and partly resting on piles, termed “crannoges” by Irish archæologists, and to the Italian villages called “terramare,” which likewise once rested on piles and were protected by ditches. From the extent of the pile-works we are able to estimate the number of the former inhabitants of the settlements supported by them. Quite as clear an idea of the number of the former inhabitants is also given by the early circumvallations on the tops of hills and shoulders of rock, which were likewise made and inhabited during the Stone Age. The co-operation of a large number of men for a common purpose is also shown in the often huge stone structures to which, on account of the size of the stones employed in their construction, the name “megalithic” structures, or gigantic stone structures, has been given. In Northern Europe they, too, belong to the Stone Age proper. The majority of these gigantic structures were originally tombs; the principle on which they are built is often repeated even in far less imposing tombs. [Illustration: THE FAMOUS GIANT CHAMBER NEAR ROSKILDE IN DENMARK