In which one of us struggles with the concept of "personality"

Having lunch with Geekman after he's spent a morning working on an equation that doesn't give him the answers he expects. Both of us have been seeing this sort of thing all over the place lately, so Geekman asks what a "borderline personality" is. "Is it like when you borderline don't have one?"

I admitted I had had to ask someone too when I saw it first the other day. They told me it was when you tend to flip from one extreme to the other in the way you feel about people and things -- i.e. putting them on a pedestal one minute, and following some small trigger event, suddenly seeing them as hell-demon spawn.*

Geekman thinks about this for a minute, then:

"I think I've got a borderline personality. One minute I was thinking that the problem with my equation was that I'd left out 2π, the next I was convinced it was √2π."

__________
* I have no idea whether that definition is correct or not, though.