When your phone's not there for you
Your phone has your whole address book in it. Which is great, until it isn't.
Nobody memorises phone numbers anymore. They're just there, in your pocket, always. Until you leave your phone in a cab. Until the battery dies and you're nowhere near a charger. Until you put it down for thirty seconds and it's gone. Until you step outside and the door locks behind you and your phone is on the other side.
Then you realise you can't recall a single digit of numbers you've called a hundred times.