THE PEECEPTION OF SPACE. (l.) 27

local-sign of being a very slippery and ambiguous sort of creature. Positionless at first, it no sooner appears in the midst of a gang of companions than it is found maintaining the strictest position of its own, and assigning place to each of its associates. How is this possible ? Must we accept what we rejected a while ago as absurd, and admit the points each to have position in se ? l Or must we suspect that our whole construction has been fallacious, and that we have tried to conjure up out of association qualities which the associates never contained ? There is no doubt a real difficulty here ; and the shortest way of dealing with it would be to confess it insoluble and ultimate. Even if position be not an intrinsic character of any one of those sensations we have called local-signs, we must still admit that there is something about everyone of them that stands for the potentiality of position, and is the ground why the local-sign, when it gets placed at all, gets placed here rather than there. If this ' something ' be inter- preted as a physiological something, . as the nerve-process that underlies the production of the feeling, it is easy to say 1 How strong the temptation to admit this may become is well seen in the following quotation from Stumpfs Psychologischer Ur sprung der Raum- vorstellung (p. 121), a work which seems to me to give on the whole the most philosophical account of the subject yet published. Stumpf says : " We hold a sheet of paper before us and ask : Can different positions be distinguished, in and of themselves, when of precisely the same colour ? They can, without doubt, and indeed in the same way and in the same sense in which two colours can be distinguished one from the other. It makes a difference in our experience, we notice, whether red is presented in this place or the other, just as it makes a difference whether green or red is offered. We recognise in both cases by simply looking at them that we have before us different species of the same genus. Red and green are both colours, but different colours as our sight assures us. Here and There in the field of vision are both positions, but different positions, as again our sight proves to us. Here, There, In that place, are specified differences of place, as green, red, blue, are of colour. So then separate positions are plainly distinguished as such in representation. Indeed they are so very distinct that identity never occurs between them (we cannot imagine two positions the same), and the same colours can be recognised as two only through the difference of their positions. To depict this difference I am naturally unable, for it is no qualitative difference ; but notwithstanding that it is a real difference and can be felt. I can moreover as little define it as I can that of the two colours (as sensations namely, not ethereal vibrations). But I can point it out, and upon him who does not know it, or denies it, force conviction. In short, then, what is the meaning of 'Two things are different in representation,' other than 'They can as such be distinguished, belong to a particular class of distinguishable contents ' ? I know not in what other sense we can talk of the difference of colours. This criterion however is just as applicable to positions ; nor do I know how difference of colours is distinguished from difference of positions." See also pp. 143-153.