Interesting, and that's probably where I heard of it, through second-hand sources. I think it's very similar to (what I understand to be) a fundamental concept

Interesting, and that's probably where I heard of it, through second-hand sources. I think it's very similar to (what I understand to be) a fundamental concept of meditation: that when a thought pops into your head, you acknowledge it, and put it aside. The notebook thing seems to be the same concept on a different level.