Thus the social services of the Intellect are not limited to revealing the existence of an external Economy, and the necessity of submission to its sway. If the theory is to have any influence upon our active powers, it should include an exact estimate of the imperfections of this economy and of the limits within which it varies, so as to indicate and define the boundaries of human intervention. Thus it will always be an important function of philosophy to criticize nature in a Positive spirit, although the antipathy to theology by which such criticism was formerly animated has ceased to have much interest, from the very fact of having done its work so effectually. The object of Positive criticism is not controversial. It aims simply at putting the great question of human life in a clearer light. It bears closely on what Positivism teaches to be the great end of life, namely, the struggle to become more perfect; which implies previous imperfection. This truth is strikingly apparent when applied to the case of our own nature, for true morality requires a deep and habitual consciousness of our natural defects. [The chief difficulty of the Positive Synthesis was to complete our conception of the External Order, by extending it to Social phenomena] I have now described the fundamental condition of the Positive Synthesis. Deriving its subjective principle from the affections, it is dependent ultimately on the intellect for its objective basis. This basis connects it with the Economy of the external world, the dominion of which Humanity accepts, and at the same time modifies. I have left many points unexplained; but enough has been said for the purpose of this work, which is only the introduction to a larger treatise. We now come to the essential difficulty that presented itself in the construction of the Synthesis. That difficulty was to discover the true Theory of human and social Development. The first decisive step in this discovery renders the conception of the Order of Nature complete. It stands out then as the fundamental doctrine of an universal system, for which the whole course of modern progress has been preparing the way. For three centuries men of science have been unconsciously co-operating in the work. They have left no gap of any importance, except in the region of Moral and Social phenomena. And now that man’s history has been for the first time systematically considered as a whole, and has been found to be, like all other phenomena, subject to invariable laws, the preparatory labours of modern Science are ended. Her remaining task is to construct that synthesis which will place her at the only point of view from which every department of knowledge can be embraced.