A lesson for us all: organising your thoughts is key. Sociologist Niklas Luhmann’s method for taking notes, Zettelkasten, which is German for note-box or slip-box, allowed him to write more than 70 books and 400 articles... all without a computer! The secret? Make notes on small slips of paper as you read and record sources, before numbering and categorising them within a network of inter-connected ideas. Productivity and serendipity!