seems to me certain that this particular argument constitutes no such reason. And I think that those who suppose that it does are apt to be influenced by an assumption, for which also, so far as I can see, there is no reason. I have admitted that the only reason I can see for supposing that sensibles which we experience ever exist unexperienced, seems to lead to the conclusion that the sensibles which would be seen by a colour-blind man, if he occupied exactly the position which I, who am not colour-blind, now occupy, exist now, just as much as those which I now see. And it may be thought that this implies that the sensibles, which he would see, and which would certainly be very different from those which I see, are nevertheless at this moment in exactly the same place as those which I see. Now, for my part, I am not prepared to admit that it is impossible they should be in the same place. But the assumption against which I wish to protest, is the assumption that, if they exist at all, they _must_ be in the same place. I can see no reason whatever for this assumption. And hence any difficulties there may be in the way of supposing that they could be in the same place at the same time as the sensibles which I see, do not at all apply to my hypothesis, which is only that they exist _now, not_ that they exist _in the same place_ in which mine do. On this question, therefore, as to whether sensibles ever exist at times when they are not experienced, I have only to say (1) that I think there is certainly no good reason whatever for asserting that _no_ sensibles do; and (2) that I think perhaps a certain amount of weight ought to be attached to our instinctive belief that certain kinds of sensibles do; and that here again any special arguments which may be brought forward to show that, whether some sensibles exist unexperienced or not, _this_ kind certainly do not, are, so far as I can see, wholly inconclusive. (II) I now pass to the question how sensibles are related to physical objects. And here I want to say, to begin with, that I feel extremely puzzled about the whole subject. I find it extremely difficult to distinguish clearly from one another the different considerations which ought to be distinguished; and all I can do is to raise, more or less vaguely, certain questions as to how certain _particular_ sensibles are related to certain _particular_ physical objects, and to give the reasons which seem to me to have most weight for answering these questions in one way rather than another. I feel that all that I can say is very tentative.