I do not lay any stress upon the argument, except in a negative sense. I do not see, that is, how Mr. Kidd can make his theory fit the facts. But I infer one other remark. It is impossible to divine the causes of the rise and fall of empires, the success or decay of a race, from any of these sweeping generalisations about ill-defined qualities. If we ask why the Greeks died out, we should have to take into account another and a totally different set of considerations: what I may call the accidents of their position. We should have to consider all the arguments by which historians have tried to explain the events; the facts of physical geography, for example, which account for the division into small separate States; the relations of the Greeks to the Eastern races on the one side, and to the Romans on the other; and, briefly, to all the material conditions, those different from the intrinsic character of the race, by which the whole course of political development and of the conflict between different peoples, is moulded and directed into particular courses. I do not say, for I cannot guess, what would be the result of such an inquiry; but I think it just as possible that it would lead us to wonder at the persistence of the Greek States for so long a period, as that it would lead us to wonder at their disappearance. Our conclusion might be, that nothing but the astonishing intellectual powers of the Greeks enabled them to play so great a part in the world's history, not that their intellectual superiority was the cause of their decay. I consider, therefore, that the alleged fact is stated so vaguely that we have no distinct problem set before us; that we don't know what is the process to be explained; that the suggested intellectual superiority is doubtful, at least in degree: that the excess of intellectual above other development, which the superiority is supposed to have created, is not proved, and, still less, that such excess was more conspicuous among the Greeks than among their rivals; that, even if it existed, it is not proved that it would have produced the effect ascribed to it; and, finally, that the other causes which undoubtedly operated, are simply overlooked. I confess, therefore, that the whole argument seems to me to illustrate the danger of rashly applying certain scientific formulæ,--themselves, perhaps, still doubtful,--to new and exceedingly complex questions. If Darwin had reasoned in this light-hearted way, no one would have been moved by his conclusions.