express by the words "I am in this room," is it certain that this idea would not be as true then as it is now? It is perhaps true that the _whale_ of what I mean by such a phrase as this never does recur. But part of it does, and that a part which is true. Part of what I mean is Certainly identical with part of what I should mean to-morrow by saying "I _was_ in that room last night." And this part would be as true then, as it is now. And is there _any_ part, which, if it were to recur at any time, would _not_ then be true, though it Is true now? In the case of all ideas or parts of ideas, which ever do actually recur, can we find a single instance of one, which is plainly true at one of the times when it occurs, and yet not true at another? I cannot think of any such instance. And on the other hand this very proposition that any idea (other than mere words) which is true once, would be true at any time, seems to me to be one of those truths of which Professor James has spoken as having an "eternal," "absolute," "unconditional" character--as being "perceptually obvious at a glance" and needing "no sense-verification." Just as we know that, if a particular colour differs more from black than from grey at one time, the same colour would differ more from black than from grey at any time, so, it seems to me, we can see that, if a particular idea is true at one time, the same idea would be true at any time. It seems to me, then, that if we mean by an idea, not mere words, but the kind of idea which words express, any idea, which is true at one time when it occurs, _would_ be true at any time when it were to occur; and that this is so, even though it is an idea, which refers to facts which are mutable. My being in this room is a fact which is now, but which certainly has not been at every time and will not be at every time. And the words "I _am_ in this room," though they express a truth now, would not have expressed one if I had used them yesterday, and will not if I use them to-morrow. But if we consider the idea which these words _now_ express--namely, the idea of the connection of my being in this room with this particular time--it seems to me evident that anybody who had thought of that connection at any time in the past, would have been thinking truly, and that anybody who were to think of it at any time in the future would be thinking truly. This seems to me to be the sense in which truths are immutable--in which no idea can change from true to false. And I think Professor James means to deny of truths generally, if not of all truths, that they are immutable even in this sense. If he does not mean this there seems nothing left for him to mean, when he says that truths are mutable, except (1) that some _facts_ are mutable, and (2) that the same _words_ may be true at one time and false at another. And it seems to me impossible that he could speak as he does, if he meant _nothing more_ than these two things.