Lewis in Weight of Glory makes the point that for any higher thing (like a three-dimensional cube) to be transposed onto a lower medium (like a two-dimensional piece of paper) two things must be true: a) the thing must lose something (in this case, a dimension) and b) in the lower medium, the transposition will be built of borrowed parts, parts which have another meaning (in other words, a triangle on a 2D paper can mean either the receding corner of a cube or, simply, a triangle).
Having said this, he goes on (and this is where I became interested) to criticise introspection on the whole. Suppose you have this really great conversation with a family member of yours. You feel really connected, it was a deep, engaging time, hours long. You finished the conversation and get in your car and drive home. While driving you look inside yourself and think, “Wow, that was so great! I wonder why that was such a good conversation.” Essentially, the argument is that that whatever you examine at that point, whatever emotional and physical properties you remember having, will be properties coincidental to what was going on, not essential to what was going on.
I do not believe this discredits introspection outright. It discredits, surely, a reliance on past nourishment for present nourishment, but there is (in my experience) much to be garnered from the memories of the days experiences.
On the other hand, I am grateful to Lewis for the insight. It gives me a vocabulary with which to understand the unrelenting fact that good conversations cannot be recounted, only re-created.