Organizing books
I just had to record this vivid memory:
When I was 18 or 19 years old, I didn't have a huge book collection, but I had enough to fill one shelf that was about 6 feet long. I remember carefully arranging my books by topic and selecting the "transition books" that connected the topics to each other. When I finished shelving the books, I felt exalted with the sense of having made relevant connections between ideas, facts, and theories and represented those connections with the particular order in which I'd arranged my books on the shelf. These ranged from text books to novels, popular science to poetry. This perfect order was precious to me because of the order it gave to my thoughts.
Then, one day, the shelf fell while I was getting a book down from it. All of my beautifully organized books were now laying in a chaotic heap on the floor.
I never did remember the exact order they were in before it fell, and that was pretty depressing. As I look at my books now, I still feel the loss of that order and I'm trying to restore it.