The principle which I shall attempt to prove is, that ideas are the offspring of the understanding, not of the senses. By a sensation is meant the perception produced by the impression of the several parts of an outward object, each by itself, on the correspondent parts of an organised sentient being: by an idea I mean the conception produced by a number of these together on the same conscious principle. Besides the succession or juxtaposition of different sensible impressions, I suppose that there is a common principle of thought, a superintending faculty, which alone perceives the relations of things, and enables us to comprehend their connexions, forms, and masses. This faculty is properly the understanding, and it is by means of this faculty that man indeed becomes a reasonable soul. What has led more than any thing else to the exclusion of the understanding as a distinct faculty of the mind, and to the principle of resolving the acts of judging, reasoning, &c., into mere association, or succession of ideas, has been the considering ideas themselves, or those particular objects which are marked by one name, or strike at once upon the senses, as _simple things_. Mr. Locke, it is true, has avoided this error as far as relates to our ideas of substances, but he reckons among simple ideas of the qualities of things several ideas, which are evidently complex, such as extension, figure, motion, and number. Hence, having laid in a certain stock of ideas without the necessity of the understanding, it was thought an easy matter to build up the whole structure of the human mind without it, as we build a house with stones. The method, therefore, which I shall take to establish the point I have in view, will be by showing that there is no one of these simple ideas, or ideas of particular things, which are made the foundation of all the rest, that is not itself an aggregate of many things, or that can subsist a moment but in the understanding. I can conceive of a being endued with the power of sensation, or simple perception, so as to receive the direct impressions of things, and also with memory, so as to retain them for any length of time, as they were severally and unconnectedly presented, yet without the smallest degree of understanding, or without ever having so much as a single thought. The state of such a being would be that of animal life, and something more with the addition of memory, but it would not amount to intellect; which implies, besides actual, living impressions, the power of perceiving their relations to one another, of comparing and contrasting them, and of regarding the different parts of any object as making one whole. Without this ‘discourse of reason,’ this surrounding and forming power, we could never have the idea of a single object, as of a table or a chair, a blade of grass, or a grain of sand. Every one of these includes a certain configuration, hardness, colour, &c., _i.e._ ideas of