One point may legitimately be regarded as attained by contemporary criticism. After the labours of Herr Roskoff, M. Réville, and M. Girard de Rialle, it is impossible to maintain that there exist nowadays on the surface of the earth whole peoples absolutely without religion or superstition, which among non-civilized people amount to the same thing.[8] The reason why man is a superstitious or religious being is simply that he possesses a high degree of intelligence. Megalithic monuments (menhirs, cromlechs, dolmens), sepulchres, amulets, are trustworthy evidence of the existence of religion in prehistoric times; and those fragments of bone detached from the skull and pierced with holes to pass a string through—“cranial rounds”—belong, no doubt, to the same category.[9] Manifestations of the religious spirit date back thus to the age of polished stone. And to pass from facts to hypotheses it is conceivable that at the beginning of the quaternary period, perhaps two hundred and fifty thousand years ago, man was already feeding upon vague and elementary superstitions, though he does not appear to have felt sufficient respect for his dead to have dug sepulchres, and although no fetiches belonging to that period have been discovered. [8] Herr Roskoff, _Das Religionswesen der rohesten Naturvoelker_ (Leipzig, 1880); M. Girard de Rialle, _Mythologie comparée_ (Paris, 1878); M. Réville, _Les religions des peuples non civilisés_ (Paris, 1880). [9] See M. G. De Mortillet, _Le préhistorique. Antiquité de l’homme_ (Paris, 1883). [Sidenote: Established fact that religion is of natural origin.] A second point which may be regarded as equally established, and which results in important consequences in the matter of method of research, is that religion, being of natural origin, must have developed slowly and in accordance with universal and regular laws; it must have originated in simple and vague notions of some sort, accessible to the most primitive intelligence. And from that starting point it must have risen by gradual evolution to the complex and precise conceptions which characterize it to-day. It is in vain for religions to believe themselves immutable; they have all of them been borne forward unwittingly by the movement of universal evolution. The great Egyptian Sphinx, who has not changed her position in the desert these four thousand years, might believe herself to be stationary, but she has never ceased for an instant to whirl through space, borne along by the earth’s motion around the sun. [Sidenote: Two contrasted theories of its origin.]