Difficult as it is to come to any definite conclusion as to the age of the monuments, it is yet more difficult to ascertain to what race their builders belonged. In the first place we ask: Are they all the work of one race? The contrary, earnestly maintained by M. de Mortillet, has long been the general opinion. M. Worsaae declared, at the Brussels Congress,29 that the dolmens were erected by different peoples; M. Cazalis de Fondouce,30 M. Broca,31 and M. Cartailhac,32 share this belief. “Are not the monuments of huge stones,” says M. Fondouce, “the product of a progressive civilization growing by degrees, rather than the work of a single people maintaining their own manners and customs in the midst of the old primitive populations they visited, without borrowing anything from their hosts?” To Broca, the resemblance between the dolmens of Europe, Africa, and even of America proves but one thing: the similarity of the aspirations and powers of all men. Everywhere, and at every time, men have aimed, in their monuments, not only at durability, but at the expression of force and of power. It was with this end in view that they erected menhirs and selected enormous stones for their megalithic monuments. The dolmen, which looks like an architectural building, is but a modification of primitive tombs. The cave-man first turned to account natural or artificial rock shelters, and when they were not to be had, he imitated them in such materials as he had at his disposal. Hence we have crypts, kistvaens, and dolmens; and the resemblance between them proves nothing as to the parentage of their builders.