Page:Essays on the Principles of Human Action (1835).djvu/188

 to produce a general effect, abstracted from the particular feelings themselves, or the objects first exciting them. All abstract ideas are several impressions of the same kind, and are merely customary affections of the mind, not distinct images of things. But if it be said that the word idea properly signifies an image, and must be something distinct, then I answer, first, that this would only restrict the use of the word idea to particular things, and not affect the real question in dispute, and secondly, that there is no such thing as a distinct and particular image in the mind. The manner in which Berkeley explains the nature of mathematical demonstrations, according to his system, shew its utter inadequateness to any purposes of general reasoning, and is a plain confession of the necessity of abstract ideas. For all the answer he gives to the question, how can we know any proposition to be true in general, from having found it so in a particular instance, comes to this, that though the diagram we have in view includes a number of particulars, yet we know the principle to be true generally, because there is not the least mention made of these particulars in the proof of the proposition. But I would ask also, whether there is not the least thought of them in the mind? The truth is, that the mind upon Berkeley's principle must think of the particular right angled, isosceles, triangle in question, or it can have no idea at all, for it has no general idea of a triangle to which it can apply the name generally. If we suppose that there is any such general form, or notion to which the other particular circumstances are merely superadded, and which may be left standing, though they are taken away, we then run immediately to all the absurdities of abstraction, which he so much wishes to avoid. If we then demonstrate the proposition of the particular diagram before us, as of a determinate size, shape, &c., this demonstration cannot hold