We see from these brief remarks that the series of the abstract sciences naturally arranges itself according to the decrease in generality and the increase in complication. We see the reason for the introduction of each member of the series, and the mutual connexion between them. The classification is evidently the same as that before laid down in my theory of development. That theory therefore may be regarded, from the statical point of view, as furnishing a direct basis for the co-ordination of Abstract conception, on which, as we have seen, the whole synthesis of human life depends. That co-ordination at once establishes unity in our intellectual operations. It realizes the desire obscurely expressed by Bacon for a _scala intellectûs_, a ladder of the understanding, by the aid of which our thoughts may pass with ease from the lowest subjects to the highest, or vice versa, without weakening the sense of their continuous connexion in nature. Each of the six terms of which our series is composed is in its central portion quite distinct from the two adjoining links; but it is closely related in its commencement to the preceding term, in its conclusion to the term which follows. A further proof of the homogeneousness and continuity of the system is that the same principle of classification, when applied more closely, enables us to arrange the various theories of which each science consists. For example, the three great orders of mathematical speculations, Arithmetic, Geometry, and Mechanics, follow the same law of classification as that by which the entire scale is regulated. And I have shown in my _Positive Philosophy_ that the same holds good of the other sciences. As a whole, therefore, the series is the most concise summary that can be formed of the vast range of Abstract truth; and conversely, all rational researches of a special kind result in some partial development of this series. Each term in it requires its own special processes of induction; yet in each we reason deductively from the preceding term, a method which will always be as necessary for purposes of instruction as it was originally for the purpose of discovery. Thus it is that all our other studies are but a preparation for the final science of Humanity. By it their mode of culture will always be influenced and will gradually be imbued with the true spirit of generality, which is so closely connected with social sympathy. Nor is there any danger of such influence becoming oppressive, since the very principle of our system is to combine a due measure of independence with practical convergence. The fact that our theory of classification, by the very terms of its composition, subordinates intellectual to social considerations, is eminently calculated to secure its popular acceptance. It brings the whole speculative system under the criticism, and at the same time under the protection of the public, which is usually not slow to check any abuse