Anytime a passage spoke to something he was working on, or reminded him of an idea previously recorded in his zettelkasten, Luhmann wrote down the page number of where the passage could be found, followed by a brief description of what was said or how it related to his thinking. On the back of the slip, Luhmann recorded bibliographic information.18

Virginia Woolf described her ideal diary: I should like it to resemble some deep old desk or capacious hold-all, in which one flings a mass of odds and ends without looking them through. I should like to come back, after a year or two, and find that the collection had sorted itself and refined itself and coalesced, as such deposits so mysteriously

He realised that one idea, one note was only as valuable as its context, which was not necessarily the context it was taken from. So he started to think about how one idea could relate and contribute to different contexts. Just amassing notes in one place would not lead to anything other than a mass of notes. But he collected his notes in his slip-