We say the Cyclops in Homer, and the Brobdignagian of Swift, are unlike. We do so precisely in the same way, as we say, the rose and the lily are unlike; and the explanation which we have given of that which is distinctively marked by those terms, when applied to objects, is precisely applicable here. In the case of objects, that which is named, is, clusters of ideas;[16] in the present case, that which is named, is clusters of ideas. That one cluster has been formed in one way, another in another, makes no difference in annexing marks to the clusters when they are formed.
[16] Say rather, in the case of objects, what is named is clusters of sensations, supplemented by possibilities of sensation. If an object is but a cluster of ideas, what is there to distinguish it from a mere thought?—Ed.
There is as little difficulty in tracing what is marked by the relatives, different, and same, when applied to ideas of this class. We say, the unicorn is different 63 from the horse; because, to the idea of the horse it adds that of a horn growing in the middle of the forehead. In the case of very complex ideas, it is much more difficult to say, with precision, what are the added and subtracted ideas, on account of which, we apply the term, different; as when we say, the courage of Ajax was different from that of Achilles; but it is not the less certain, that it is wholly on account of ideas added and subtracted, that we so denominate the courage of the two men.
Rather more explanation is needed, to shew what is peculiarly marked by the relatives equal, unequal, greater, less, when applied to the class of arbitrarily formed complex ideas.
We have already seen, that those terms are primarily applied to what we call objects, on account of their extension; objects are equal or unequal, greater or less, in extension.
We have also seen, that in marking the extension of different objects, we are under the necessity of taking some known object as a standard, and by that object naming others. Thus, we take the foot, and say that other objects are two feet, three feet, or the half or quarter of a foot, and so on.
Having become familiar with what we call degrees of extension, we are led to employ the same mode of notation, when we come to mark analogous differences in other cases of sensation. Thus, when we perceive the weight of different heavy bodies; as the terms equal, unequal, greater, less, are applied with convenience to certain cases of extension, it appears they may be applied with equal convenience, and even precision, to cases of weight. All other sensations, 64 having distinguishable differences, may be marked in the same way: thus sounds are more or less loud, and we speak of equal, or unequal, less or greater loudness of sound; less or greater sweetness in objects of the palate; less or greater resistance; less or greater pain; less or greater pleasure.
When the terms equal, unequal, less, greater, had been applied to simple sensations of the pleasurable kind, and their ideas; the transference of them to complex ideas, of the pleasurable or painful kind, was easy. If the less or greater sweetness of the rose and the woodbine, was a convenient notation, so was the less or greater beauty of those two flowers, the less or greater beauty of two women, the less or greater wisdom or folly, vice or virtue, of two men.
It thus appears, that, as we apply the term unlike to our complex ideas, on account of the addition and subtraction of ideas of different kinds, so we apply to them the term unequal, on account of the addition and subtraction of ideas of the same kind. Like and equal we apply, when we neither add, nor subtract.[17]
[17] In this passage the author has got as near as it is perhaps possible to get, to an analysis of the ideas of More and Less. We say there is more of something, when, to what there already was, there has been superadded other matter of the same kind. And when there is no actual superadding, but merely two independent masses of the same substance, we call that one the greater which produces the same impression on our senses which the other would produce if an addition were made to it. So with differences of intensity. One sweet taste is called sweeter than another because it resembles the taste which would be produced by adding more sugar: and so forth. In all these cases there is presupposed an original difference in the sensations produced in us by the greater mass and by the smaller: but according to the explanation now offered, the idea which guides the application of the terms is that of physical juxtaposition.—Ed.