I’ve tried Evernote and Scrivener, paper planners and Moleskines, and seemingly every app under the sun to capture my ideas. But I keep coming back to one simple, underrated tool to catch those ...

Simply sign up to the Life & Arts myFT Digest -- delivered directly to your inbox. Nabokov used them. Wittgenstein did, too. But only Niklas Luhmann made the humble index card his magnum opus. The ...