Overlooking the obvious

I'd like to believe that my memory is generally good and that I usually remember to take care of my most important obligations.  One night when I was in high school, however, I drove off to jazz band rehearsal, making a detour at the library first.  I'd been so determined to return several books on time that I'd been reminding myself of it all day.  After turning the books in, I headed to school.  When I got there, I opened the trunk of the car--and realized that I'd forgotten to bring my upright bass.  Anyone who has ever seen upright basses knows that they're bulky and nearly impossible to forget; somehow, that night, I was so focused on returning library books that I neglected to put the bass in the car.  Luckily, the jazz band director laughed it off and said it was fine for me to go home and get the bass.  His one piece of advice?  "Maybe, leave a note on it next time."