A multitude of subordinate wheels depend on the great central wheel. For if the clock runs， it is owing to the harmony of its various parts， from which it follows that， on this harmony ceasing， the clock gets out of order. But， besides the principal spring， there are others which， acting on or in combination with it， give to each clock a special character and a peculiar movement. Such， in the first place， is climate， that is to say， the degree of heat or cold， humidity or dryness， with its infinite effects on man's physical and moral attributes， followed by its influence on political， civil and domestic servitude or freedom. Likewise the soil， according to its fertility， its position and its extent. Likewise the physical régime， according as a people is composed of hunters， shepherds or agriculturists. Likewise the fecundity of the race， and the consequent slow or rapid increase of population， and also the excess in number， now of males and now of females. And finally， likewise， are national character and religion. - All these causes， each added to the other， or each limited by the other， contribute together to form a total result， namely society. Simple or complex， stable or unstable， barbarous or civilized， this society contains within itself its explanations of its being. Strange as a social structure may be， it can be explained； also its institutions， however contradictory.
Neither prosperity， nor decline， nor despotism， nor freedom， is the result of a throw of the dice， of luck or an unexpected turn of events caused by rash men. They are conditions we must live with. In any event， it is useful to understand them， either to improve our situation or bear it patiently， sometimes to carry out appropriate reforms， sometimes to renounce impracticable reforms， now to assume the authority necessary for success， and now the prudence making us abstain.
IV. THE NEW PSYCHOLOGY.
The transformation of psychology. - Condillac. - The theory of sensation and of signs.
We now reach the core of moral science； the human being in general. The natural history of the mind must be dealt with， and this must be done as we have done the others， by discarding all prejudice and adhering to facts， taking analogy for our guide， beginning with origins and following， step by step， the development by which the infant， the savage， the uncultivated primitive man， is converted into the rational and cultivated man. Let us consider life at the outset， the animal at the lowest degree on the scale， the human being as soon as it is born. The first thing we find is perception， agreeable or disagreeable， and next a want， propensity or desire， and therefore at last， by means of a physiological mechanism， voluntary or involuntary movements， more or less accurate and more or less appropriate and coordinated. And this elementary fact is not merely primitive； it is， again， constant and universal， since we encounter it at each moment of each life， and in the most complicated as well as in the simplest. Let us accordingly ascertain whether it is not the thread with which all our mental cloth is woven， and whether its spontaneous unfolding， and the knotting of mesh after mesh， is not finally to produce the entire network of our thought and passion. - Condillac (1715-1780)provides us here with an incomparable clarity and precision with the answers to all our questions， which， however the revival of theological prejudice and German metaphysics was to bring into discredit in the beginning of the nineteenth century， but which fresh observation， the establishment of mental pathology， and dissection have now (in 1875) brought back， justified and completed.[23] Locke had already stated that our ideas all originate in outward or inward experience. Condillac shows further that the actual elements of perception， memory， idea， imagination， judgment， reasoning， knowledge are sensations， properly so called， or revived sensations； our loftiest ideas are derived from no other material， for they can be reduced to signs which are themselves sensations of a certain kind. Sensations accordingly form the substance of human or of animal intelligence； but the former infinitely surpasses the latter in this， that， through the creation of signs， it succeeds in isolating， abstracting and noting fragments of sensations， that is to say， in forming， combining and employing general conceptions. - This being granted， we are able to verify all our ideas， for， through reflection， we can revive and reconstruct the ideas we had formed without any reflection. No abstract definitions exist at the outset； abstraction is ulterior and derivative； foremost in each science must be placed examples， experiences， evident facts；from these we derive our general idea. In the same way we derive from several general ideas of the same degree another general idea， and so on successively， step by step， always proceeding according to the natural order of things， by constant analysis， using expressive signs， as with mathematicians in passing from calculation by the fingers to calculation by numerals， and from this to calculation by letters， and who， calling upon the eyes to aid Reason， depict the inward analogy of quantities by the outward analogy of symbols. In this way science becomes complete by means of a properly organized language.[24] -Through this reversal of the usual method we summarily dispose of disputes about words， escape the illusions of human speech， simplify study， remodel education， enhance discoveries， subject every assertion to control， and bring all truths within reach of all understandings.
V. THE ANALYTICAL METHOD.
The analytical method. - Its principle. - The conditions requisite to make it productive. - These conditions wanting or inadequate in the 18th century. - The truth and survival of the principle.