If you write down a lot of your ideas, it's easy to forget about them as time moves on. University professor Bodong Chen points out that it's worth going back to old notes to spark new ideas.
Using Charles Darwin's notes as an example, Chen lays out the usefulness of returning to old ideas:
Keeping a slow hunch alive poses challenges on multiple scales. For starters, you have to preserve the hunch in your own memory, in the dense network of your neurons. So part of the secret of hunch cultivation is simple: write everything down… We can see Darwin's ideas evolve because on some basic level the notebook platform creates a cultivating space for his hunches; it is not that the notebook is a mere transcription of the ideas, which are happening offstage somewhere in Darwin's mind. Darwin was constantly rereading his notes, discovering new implications. His ideas emerge as a kind of duet between the present-tense thinking brain and all those past observations recorded on paper.
Likewise, we talk a lot about organising your notes, but it's sometimes best to just let that stuff mix together because when you return to them, you'll see two unrelated things in a new light.