but it is not easy for a common reader to discern or to explain it. Considering the cranium, according to what he conceives to be the true anatomical theory, as simply a prolongation of the vertebral column,--the primitive centre of the whole nervous system,--he argues that the functions, intellectual and emotional, which are proper to the upper and anterior parts of it, are less energetic than the animal propensities, whose organs lie in the lower and posterior region, just in proportion as they are further removed from the spine; and that, for this reason, the latter must first come into action, then the intermediate organs of sentiment, and, last of all, the intellectual powers. And this doctrine he applies to the verification both of his otherwise admirable classification of the Sciences, and of his far more doubtful law of human development. We conceive that if it were applicable at all to the problem of human progress, it might possibly be applied to indicate the probable development of an _individual mind_, in the successive stages of infancy, youth, and manhood; but that it does not admit of the same application to _the history of the race_, otherwise than by the aid of a very fanciful analogy. We have no faith in the _a priori_ methods of constructing the chart of human history, and tracing the necessary course of social progress, which have recently become so popular in Germany and France. We cannot, with M. Comte, undertake to solve the problem,--Given three lobes of the brain, representing the propensities, affections, and intellectual powers, but differing from each other in size and situation, what will be the future history of the race,--religious, aesthetic, industrial, metaphysical, social? We cannot, with M. Cousin, undertake to solve the problem,--Given three terms, the finite, the infinite, and the relation between the two, what will be the development of human thought, first, in the experience of individuals, and, secondly, in the history of society?[72] All such problems are too high for us. The history of the human race must be ascertained from the authentic records and extant monuments of the past, not constructed by theories, or divined by _a priori_ speculations.