(_b_) To get at the other sense of “idea” we should think {75} of the meaning of a word; a very simple case is that of a proper name. What is the meaning of “St. Paul’s Cathedral in London”? No two people who have seen it have carried away precisely the same image of it in their minds, nor does memory, when it represents the Cathedral to each of them, supply the same image in every detail and association twice over to the same person, nor do we for a moment think that such an image _is_ the Cathedral. [1] Yet we neither doubt that the name _means_ something, and that the same to all those who employ it, nor that it means the same to each of them at one time that it did at every other time. The psychical images which formed the first vision of it are dead and gone for ever, and so, after every occasion on which it has been remembered, are those in which that memory was evoked. The essence of the idea does not lie in the peculiarities of any one of their varying presentations, but in the identical reference that runs through them all, and to which they all serve as material, and the content of this reference _is_ the object of our thought. [1] When we are actually looking at the Cathedral, we say, “_That is_ the Cathedral.” Does not this mean that we take our momentary image, to which we point, to be the reality of the Cathedral? Not precisely so. It is the “that,” not our definite predication about it, which makes us so confident. The “that” is identified by our judgment, but goes beyond it. In order to distinguish and employ this reference it is necessary that there should be a symbol for it, and so long as it brings us to the object which is the centre of the entire system, this symbol may vary within considerable limits.