and the elementary states of consciousness under consideration will stand thus: A. IMPRESSIONS. A. Sensations of b. Taste. c. Hearing. d. Sight. e. Touch. f. Resistance (the muscular sense). B. Pleasure and Pain. c. Relations. a. Co-existence. b. Succession. c. Similarity and dissimilarity. B. IDEAS. Copies, or reproductions in memory, of the foregoing. And now the question arises, whether any, and if so what, portion of these contents of the mind. are to be termed "knowledge?" According to Locke, "Knowledge is the perception of the agreement or disagreement of two ideas;" and Hume, though he does not say so in so many words, tacitly accepts the definition. It follows, that neither simple sensation, nor simple emotion, constitutes knowledge; but that, when impressions of relation are added to these impressions, or their ideas, knowledge arises; and that all knowledge is the knowledge of likenesses and unlikenesses, co-existences and successions. It really matters very little in what sense terms are used, so long as the same meaning is always rigidly attached to them; and, therefore, it is hardly worth while to quarrel with this generally accepted, though very arbitrary, limitation of the signification of "knowledge." But, on the face of the matter, it is not obvious why the impression we call a relation should have a better claim to the title of knowledge, than that which we call a sensation or an emotion; and the restriction has this unfortunate result, that it excludes all the most intense states of consciousness from any claim to the title of "knowledge." For example, on this view, pain, so violent and absorbing as to exclude all other forms of consciousness, is not knowledge; but becomes a part of knowledge the moment we think of it in relation to another pain, or to some other mental phenomenon. Surely this is somewhat inconvenient, for there is only a verbal difference between having a sensation and knowing one has it: they are simply two phrases for the same mental state. But the "pure metaphysicians" make great capital out of the ambiguity. For, starting with the assumption that all knowledge is the perception of relations, and finding themselves like mere common-sense folks, very much disposed to call sensation knowledge, they at once gratify that disposition and save their consistency, by declaring that even the simplest act of sensation contains, two terms and a relation—the sensitive subject the sensigenous object, and that masterful entity, the Ego. From which great triad, as from a gnostic Trinity, emanates an endless procession of other logical shadows and all the Fata Morgana of philosophical dreamland. CHAPTER III THE ORIGIN OF THE IMPRESSIONS ADMITTING that the sensations, the feelings of pleasure and pain, and those of relation, are the primary irresolvable states of consciousness, two further lines of investigation present themselves. The one leads us to seek the origin of these "impressions:" the other, to inquire into the nature of the steps by which they become metamorphosed into those compound states of consciousness, which so largely enter into our ordinary trains of thought. With respect to the origin of impressions of sensation, Hume is not quite consistent with himself. In one place (I. p. 117) he says, that it is impossible to decide" whether they arise immediately from the object, or are produced by the creative power of the mind, or are derived from the Author of our being," thereby implying that realism and idealism are equally probable hypotheses. But, in fact, after the demonstration by Descartes, that are the immediate antecedents of sensations changes in the nervous system, with which our feelings have no sort of resemblance, the hypothesis that sensations "arise immediately from the object" was out of court; and that Hume fully admitted the Cartesian doctrine is apparent when he says (I. p. 272): "All our perceptions are dependent on our organs and the disposition of our nerves and animal spirits." And again, though in relation to another question, he observes : "There are three different kinds of impressions conveyed by the senses. The first are those of the figure, bulk, motion, and solidity of bodies. The second those of colours, tastes, smells, sounds, heat, and cold. The third are the pains and pleasures that arise from the application of objects to our bodies, as by the cutting of our flesh with steel, and such like. Both philosophers and the vulgar suppose the first of these to have a distinct continued existence. The vulgar only regard the second as on the same footing. Both philosophers and the vulgar again esteem the third to be merely perceptions, and consequently interrupted and dependent beings. "Now 'tis evident that, whatever may be our philosophical opinion, colour, sounds, heat, and cold, as far as appears to the senses, exist after the same manner with motion and solidity; and that the difference we make between them, in this respect, arises not from the mere perception. So strong is the prejudice for the distinct continued existence of the former qualities, that when the contrary opinion is advanced by modern philosophers, people imagine they can almost refute it from their reason and experience, and that their very senses contradict this philosophy. "Tis also evident that colours, sounds, &c., are originally on the same footing with the pain that arises from steel, and pleasure that proceeds from |