Twenty years ago I drove thirty-five miles to Pasadena to see a patient. When I opened the trunk to get my bag, it wasn't there. I had left it at home. I drove back to retrieve it.

Years later I made a visit to the Hyatt Regency in Long Beach, also thirty-five miles away. I had my bag, but when I consulted my invoice while waiting for the elevator, there was no room number.

I recalled how it happened. I had never been to that Hyatt Regency, so I had stopped filling out the invoice at home to look up its address on the internet. I found it, copied it down, and forgot to add the room number from my telephone notepad. Departing from your routine is always perilous.

Worse, the patient was a woman. In those years (certainly not today) when a couple checked in, it was the man whose name went on the register - and couples sometimes don't share a last name. That was the case this time as I listened with a sinking heart as the desk clerk assured me that the guest list contained no such person.

Mike Oppenheim