[Distinction between Abstract and Concrete laws. It is the former only that we require for the purpose before us] In order to give a more precise conception of the intellectual basis on which the system of Positive Polity should rest, I must explain the general principle by which it should be limited. It should be confined to what is really indispensable to the construction of that Polity. Otherwise the intellect will be carried away, as it has been before, by its tendency to useless digressions. It will endeavour to extend the limits of its province; thereby escaping from the discipline imposed by social motives, and putting off all attempts at moral and social regeneration for a longer time than the construction of the philosophic basis for action really demands. Here we shall find a fresh proof of the importance of my theory of development. By that discovery the intellectual synthesis may be considered as having already reached the point from which the synthesis of affections may be at once begun; and even that of actions, at least in its highest and most difficult part, morality properly so called. With the view of restricting the construction of the objective basis within reasonable limits, there is this distinction to be borne in mind. In the Order of Nature, there are two classes of laws; those that are simple or Abstract, those that are compound or Concrete. In my work on _Positive Philosophy_, the distinction has been thoroughly established, and frequent use has been made of it. It will be sufficient here to point out its origin and the method of applying it. Positive science may deal either with objects themselves as they exist, or with the separate phenomena that the objects exhibit. Of course we can only judge of an object by the sum of its phenomena; but it is open to us either to examine a special class of phenomena abstracted from all the beings that exhibit it, or to take some special object, and examine the whole concrete group of phenomena. In the latter case we shall be studying different systems of existence; in the former, different modes of activity. As good an example of the distinction as can be given is that, already mentioned, of Meteorology. The facts of weather are evidently combinations of astronomical, physical, chemical, biological, and even social phenomena; each of these classes requiring its own separate theories. Were these abstract laws sufficiently well known to us, then the whole difficulty of the concrete problem would be so to combine them, as to deduce the order in which each composite effect would follow. This, however, is a process which seems to me so far beyond our feeble powers of deduction, that, even supposing our knowledge of the abstract laws perfect, we should still be obliged to have recourse to the inductive method.