Variations in the aspect of man are best seen when an examination is made of nations arranged in a northerly and southerly direction, the differences of climate being much greater in this direction than from east to west. These variations do not affect complexion, development of the brain, and, therefore, intellectual power, only. But differences of manners and customs, that is, differences in the modes of civilization, must coexist with diversities of climate. An ethnical element is therefore necessarily of a dependent nature; its durability arises from its perfect correspondence with the conditions by which it is surrounded. Whatever can affect that correspondence will touch its life. With such considerations the author passes from individuals to groups of men or nations: 'There is a progress for races of men as well marked as the progress of one man. There are thoughts and actions appertaining to specific periods in the one case as in the other. Without difficulty we affirm of a given act that it appertains to a given period. We recognize the noisy sports of boyhood, the business application of maturity, the feeble garrulity of old age. We express our surprise when we witness actions unsuitable to the epoch of life. As it is in this respect in the individual, so it is in the nation. The march of individual existence shadows forth the march of race existence, being, indeed, its representative on a little scale. Groups of men, or nations, are distributed by the same accidents, or complete the same cycle as the individual. Some scarcely pass beyond infancy; some are destroyed on a sudden; some die of mere old age. In this confusion of events, it might seem altogether hopeless to disentangle the law which is guiding them all, and demonstrate it clearly. Of such groups each may exhibit, at the same moment, an advance to a different stage, just as we see in the same family the young, the middle aged, and the old. * * * In each nation, moreover, the contemporaneously different classes, the educated and illiterate, the idle and industrious, the rich and poor, the intelligent and superstitious, represent different contemporaneous stages of advancement. One may have made a great progress, another scarcely have advanced at all. How shall we ascertain the real state of the case? Which of these classes shall we regard as the truest and most perfect type?'