It would seem that the author of the 'Analysis' either could not help asking himself questions like these, or, without asking the questions, could not help seeing the commonplace truths involved in the inevitable replies to them. It would seem to have been semi-consciousness of the utter inability of the evidence first cited by him to justify belief in the necessarily simultaneous or successive occurrence of the ideas of simultaneously or successively experienced sensations, which made him have recourse for help to _complex_ ideas. 'If,' he says, 'from a stone I have had synchronically the sensation of colour, the sensation of hardness, the sensations of shape and size, the sensation of weight,--when the idea of one of these sensations occurs, the ideas of all of them occur.' Because, then, I may have ascertained by experience that a stone is white, hard, and round, two feet in diameter, and twenty pounds in weight, am I really incapable, if I happen to break my shin against it, of thinking how hard it is, without thinking also how heavy; or, when trying to lift it, of thinking how heavy it is without thinking likewise of its shape and colour? Elsewhere the same writer speaks of 'ideas which have been so often conjoined that whenever one exists in the mind, the others immediately exist along with it, seem to run into one another, to coalesce, as it were, and out of many to form one idea.' But which are the ideas whereof this can be said? The writer instances those simple ideas, colour, hardness, extension, weight, which, he says, make up our complex ideas of gold or iron. He instances, too, the ideas of resistance, muscular contractility, direction, extension, place, and motion, of which he says our apparently simple idea, weight, is compounded. Does he mean, then, that we cannot entertain the idea of yellowness without entertaining at the same time all the other ideas necessary for composing the idea of gold, and entertaining, too, that idea in addition to all the rest? Does he mean that a train of thought cannot commence with place without terminating with weight? Of course he means nothing of the kind, although so he distinctly says. Rather, he appears to mean the direct converse, viz., that we cannot have the idea of gold or of weight present to the mind, without having present also all the simple ideas of which those complex ideas are compounded--in other words, not that the occurrence of any one component necessarily calls up all the other components, and forms with them the compound, but that the appearance of the compound brings with it all its separate components.