Although I am a firm believer in leaving work at work, I always keep the office door of my brain open in case some bright idea needs to get in or out. And, that very often happens—even more often at inopportune times. I might be streaming the latest (or last!) episode of Mad Men and have to shout: “Pause, please!” so I can write myself a note. Or, I might wake in the night and send an email to my work address containing a barely comprehensible message that I need to decode the next day. Here’s one that was in my inbox this morning: