But I keep coming back to one simple, underrated tool to catch those half-baked ideas and thoughts that don’t seem to fit in anywhere else. The perfect place is the humble index card.

The index card got into Google's news results. It got into big newspapers. Famous economists tweeted about it. Self-help sites like Lifehacker mentioned it. In short, it went viral. The ideas on ...

Come exam day, the scholar must prove mastery of a field, whether it’s Islamic art or German history ... I bought a lifetime supply of index cards. On each four-by-six rectangle, I distilled ...