What more remains to be said may be despatched more summarily. Its interest is philosophic rather than practical. In his four volumes of “Politique Positive,” M. Comte revises and reelaborates the scientific and historical expositions of his first treatise. His object is to systematize (again to systematize) knowledge from the human or subjective point of view, the only one, he contends, from which a real synthesis is possible. For (he says) the knowledge attainable by us of the laws of the universe is at best fragmentary, and incapable of reduction to a real unity. An objective synthesis, the dream of Descartes and the best thinkers of old, is impossible. The laws of the real world are too numerous, and the manner of their working into one another too intricate, to be, as a general rule, correctly traced and represented by our reason. The only connecting principle in our knowledge is its relation to our wants, and it is upon that we must found our systematization. The answer to this is, first, that there is no necessity for an universal synthesis; and secondly, that the same arguments may be used against the possibility of a complete subjective, as of a complete objective systematization. A subjective synthesis must consist in the arrangement and co-ordination of all useful knowledge, on the basis of its relation to human wants and interests. But those wants and interests are, like the laws of the universe, extremely multifarious, and the order of preference among them in all their different gradations (for it varies according to the degree of each) cannot be cast into precise general propositions. M. Comte’s subjective synthesis consists only in eliminating from the sciences everything that he deems useless, and presenting as far as possible every theoretical investigation as the solution of a practical problem. To this, however, he cannot consistently adhere; for, in every science, the theoretic truths are much more closely connected with one another than with the human purposes which they eventually serve, and can only be made to cohere in the intellect by being, to a great degree, presented as if they were truths of pure reason, irrespective of any practical application.