There is no need here to enter into any criticism of Montesquieu's great work, how far the merits of its execution equalled the merit of its design, how far his vicious confusion of the senses of the word 'law' impaired the worth of his book, as a contribution to inductive or comparative history. We have only to seek the difference between the philosophic conception of Montesquieu and the philosophic conception of Turgot. The latter may be considered a more liberal completion of the former. Turgot not only sees the operation of law in the movements and institutions of society, but he interprets this law in a positive and scientific sense, as an ascertainable succession of social states, each of them being the cause and effect of other social states. Turgot gives its deserved prominence to the fertile idea of there being an ordered movement of growth or advance among societies; in other words, of the civilisation of any given portion of mankind having fixed conditions analogous to those of a physical organism. Finally, he does not limit his thought by fixing it upon the laws and constitutions only of countries, but refers historical philosophy to its veritable and widest object and concern, the steps and conditions of the progression of the human mind. How, he inquires, can we seize the thread of the progress of the human mind? How trace the road, now overgrown and half-hidden, along which the race has travelled? Two ideas suggest themselves, which lay foundations for this inquiry. For one thing, the resources of nature and the fruitful germ of all sorts of knowledge are to be found wherever men are to be found. 'The sublimest attainments are not, and cannot be, other than the first ideas of sense developed or combined, just as the edifice whose height most amazes the eye, of necessity reposes on the very earth that we tread; and the same senses, the same organs, the spectacle of the same universe, have everywhere given men the same ideas, as the same needs and the same dispositions have everywhere taught them the same arts.' Or it might be put in other words. There is identity in human nature, and repetition in surrounding circumstance means the reproduction of social consequences. For another thing, 'the actual state of the universe, by presenting at the same moment on the earth all the shades of barbarism and civilisation, discloses to us as in a single glance the monuments, the footprints of all the steps of the human mind, the measure of the whole track along which it has passed, the history of all the ages.'