First, variability is the essential condition of all race progress by biological adaptation; for it is by the selection of variations, the survival and multiplication of types varying in certain directions in larger proportions than the average type, that all race progress and adaptation seems to have been achieved. Hence, increased variability, resulting from the blending of races, will render a people so formed capable of race progress and of more rapid adaptation; for example, in the peoples of Northern Europe it would have favoured the adaptation of the constitutions of the people to the severity of the climate and to those peculiar social conditions which, as we have seen reason to believe, have been the source of their unique combination of qualities. Secondly, variability of mental qualities would be favourable to the coming of the age of discussion; for in such a people custom would rule with less force, its sway would be more apt to be questioned and disputed, than among a highly homogeneous people. Thirdly, and this is probably the most important manner in which race blending has favoured the progress of nations, among the variations from the average type produced by race crossing would be men of exceptional capacities in various directions. We have already noted that all progress of the intellectual and moral traditions eventually depends upon the activities of men of exceptional powers of various kinds, upon the great religious or ethical teacher, the inventor, the artist, the discoverer. A people may, like the Chinese, have a high average capacity of intellectual ability; but, if it cannot from time to time produce men of far more than average capacity along various lines, it will not progress very far spontaneously. Exceptional intellectual capacity is, however, a variation from the type, as the biologists say, just such as may be expected to result from race blending; there will be, among the variations in all directions, variations in the direction of exceptional capacity of various kinds. Hence a nation of blended variable stocks will, other things being the same, be far more likely to be capable of continued evolution than a homogeneous people of equal average mental capacity, among whom few men are capable of rising to any distinguished height. This view of the effects of race blending is borne out empirically by the comparison of the peoples of the world. The European peoples have been the most progressive, and they, more than all others, have been formed by repeated blendings of allied stocks. Within Europe it is the peoples among whom this blending has been carried furthest who have proved most progressive—the French, the English, and the Italian; and, conversely, the least blended peoples have been the most backward, and have contributed least to the general progress of civilisation in Europe; for example the large, almost purely Slav, population which forms the bulk of the Russian nation.