And just as I may say that such a set of three points imagined or observed now is the same with another and a similar set imagined or observed at some former time, meaning by the word same to indicate similarity, and not sameness in the strict sense mentioned just above; so there appears no reason at all why I may not say that the mutual relations of the one set of points are the same with the mutual relations of the other, making here, too, the distinction between sameness in the former, stricter, sense, and sameness in this second sense of similarity. If what is contained in a consciousness at any one instant, is, _ipso facto_, to be distinguished from what is contained in it at any other instant, there seems equal reason for making this distinction in the material element and in the formal. It is quite true that men are not accustomed to carrying this distinction into the region of form. The whole history of the dispute as to universals is evidence of the way in which men have confounded the kinds of sameness; but I fancy that even those who would clearly recognize that red color imagined yesterday and red color imagined to-day are the same merely in being similar, or in standing in a relation of original and representative, would yet not think of distinguishing triangularity noticed yesterday from triangularity noticed to-day, and marking that they are not the same in the first and strictest sense of the word. And yet it would be hard to show why two indistinguishably similar color sensations, existing in consciousness at different times, are to be kept apart in thought and recognized as two sensations, while two occurrences of the consciousness of triangularity (I use the clumsy phrase to avoid any question-begging word), are not to be distinguished as separate in a similar way. To say that the formal element is not a thing, but an activity, does not alter the position. If an activity is enough of a thing to be talked about and distinguished from other things, we may surely recognize an activity in consciousness yesterday as numerically different from an activity in consciousness to-day.