From all analogy we may be confident that the early palæolithic men who shaped the symmetrical axes of Acheul, scrapers, punches, and hammers; who carefully selected and tested the flint-flakes; who had enough of an eye for beauty to preserve fine quartz pebbles; and who lived in social groups, in stationary homes along watercourses,—these men unquestionably had a spoken language, and minds competent to deal in simple abstractions. Yet these are the most ancient men of whom we know anything, dwellers in central Europe before the Great Ice Age. When we have such evidence as this for the psychical unity of the human species, is it worth while going into that antiquated discussion of the “monogenists” and “polygenists” as to whether man owns one or several birthplaces? Surely not. We declare all nations of the earth to be of one blood by the judgment of a higher court than anatomy can furnish; though it also hands down no dissenting opinion. _The Elementary Ideas and their Development._—These two principles, or rather demonstrated truths,—the unity of the mind of man, and the substantial uniformity of its action under like conditions,—form the broad and secure foundation for Ethnic Psychology. They confirm the validity of its results and guarantee its methods. As there are conditions which are universal, such as the structure and functions of the body, its general relations to its surroundings, its needs and powers, these developed everywhere at first the like psychical activities, or mental expressions. They constitute what Bastian has happily called the “elementary ideas” of our species. In all races, over all continents, they present themselves with a wonderful sameness, which led the older students of man to the fallacious supposition that they must have been borrowed from some common centre. Nor are they easily obliterated under the stress of new experiences and changed conditions. With that tenacity of life which characterises simple and primitive forms, they persist through periods of divergent and higher culture, hiding under venerable beliefs, emerging with fresh disguises, but easily detected as but repetitions of the dear primordial faiths of the race. _The Ethnic Ideas and their Origin._—From the monotonous unity of the elementary ideas, the common property of mankind in its earliest stages of development, branched off the mental life of each group and tribe, not discarding the old, but adding the new under the external compulsion of environment and experience. Where such externals were alike or nearly so, the progress was parallel; where unlike, it was divergent; analogous in this to well-known doctrines of the biologist.