Again, did I know nothing about the movement of bodies, except what the theory of gravitation supplies, were I simply absorbed in that theory so as to make it measure all motion on earth and in the sky, I should indeed come to many right conclusions, I should hit off many important facts, ascertain many existing relations, and correct many popular errors: I should scout and ridicule with great success the old notion, that light bodies flew up and heavy bodies fell down; but I should go on with equal confidence to deny the phenomenon of capillary attraction. Here I should be wrong, but only because I carried out my science irrespectively of other sciences. In like manner, did I simply give myself to the investigation of the external action of body upon body, I might scoff at the very idea of chemical affinities and combinations, and reject it as simply unintelligible. Were I a mere chemist, I should deny the influence of mind upon bodily health; and so on, as regards the devotees of any science, or family of sciences, to the exclusion of others; they necessarily become bigots and quacks, scorning all principles and reported facts which do not belong to their own pursuit, and thinking to effect everything without aid from any other quarter. Thus, before now, chemistry has been substituted for medicine; and again, political economy, or intellectual enlightenment, or the reading of the Scriptures, has been cried up as a panacea against vice, malevolence, and misery. Summing up, Gentlemen, what I have said, I lay it down that all knowledge forms one whole, because its subject-matter is one; for the universe in its length and breadth is so intimately knit together, that we cannot separate off portion from portion, and operation from operation, except by a mental abstraction; and then again, as to its Creator, though He of course in His own Being is infinitely separate from it, and Theology has its departments towards which human knowledge has no relations, yet He has so implicated Himself with it, and taken it into His very bosom, by His presence in it, His providence over it, His impressions upon it, and His influences through it, that we cannot truly or fully contemplate it without in some main aspects contemplating Him. Next, sciences are the results of that mental abstraction, which I have spoken of, being the logical record of this or that aspect of the whole subject-matter of knowledge. As they all belong to one and the same circle of objects, they are one and all connected together; as they are but aspects of things, they are severally incomplete in their relation to the things themselves, though complete in their own idea and for their own respective purposes; on both accounts they at once need and subserve each other. And further, the comprehension of the bearings of one science on another, and the use of each to each, and the location and limitation and adjustment and due appreciation of them all, one with another, this belongs, I conceive, to a sort of science distinct from all of them, and in some sense a science of sciences, which is my own conception of what is meant by Philosophy, in the true sense of the word, and of a philosophical habit of mind, and which in these Discourses I shall call by that name. This is what I have to say about knowledge and philosophical knowledge generally; and now I proceed to apply it to the particular science, which has led me to draw it out. I say, then, that the systematic omission of any one science from the catalogue prejudices the accuracy and completeness of our knowledge altogether, and that, in proportion to its importance. Not even Theology itself, though it comes from heaven, though its truths were given once for all at the first, though they are more certain on account of the Giver than those of mathematics, not even Theology, so far as it is relative to us, or is the Science of Religion, do I exclude from the law to which every mental exercise is subject, viz., from that imperfection, which ever must attend the abstract, when it would determine the concrete. Nor do I speak only of Natural Religion; for even the teaching of the Catholic Church, in certain of its aspects, that is, its religious teaching, is variously influenced by the other sciences. Not to insist on the introduction of the Aristotelic philosophy into its phraseology, its explanation of dogmas is influenced by ecclesiastical acts or events; its interpretations of prophecy are directly affected by the issues of history; its comments upon Scripture by the conclusions of the astronomer and the geologist; and its casuistical decisions by the various experience, political, social, and psychological, with which times and places are ever supplying it.