In this excerpt from William James' discussion, I am not sure I understand what is meant by the last phrase: "snug in its own skin". But I guess it must mean "with its own peculiar qualities", right?
This way of thinking about memory is, in one or other of its slightly updated disguises, still surprisingly common, and yet it is obviously untenable for a diversity of reasons. Take first the case of what are now termed "episodic" or "autobiographical" memories, memories of oneself witnessing things or doing or participating in events or activities. Certainly one might conceivably relive one's original experience, and indeed relive it again and again, because of the changes it had brought about in one's brain. But, as William James (1890b) put it over a century ago (and he was just one of a number who made the same point in their various terminologies):'
The first element which [memory] knowledge involves would seem to be the revival in the mind of an image or copy of the original event. And it is an assumption made by many writers that the revival of an image is all that is needed to constitute the memory of the original occurrence. But such a revival is obviously not a memory, whatever else it may be; it is simply a duplicate, a second event, having absolutely no connection with the first event except that it happens to resemble it....The successive editions of a feeling are so many independent events, each snug in its own skin. (vol. I, pp. 649-650) (E. F. Kelly et al. Irreducible Mind..., pp. 243-4)