What is the essence of a bike?

[Wahine]

My BF is a bike addict. I'm not complaining... I am too. It's just a little background. He has a rule that he can't get more than one new bike a year. So he built himself an amazing Cinelli earlier this year. Now he's stripping another bike he has, using all the stripped parts and having a new frame built that will incorporate dropouts that he designed and had machined for the other frame. When I mentioned that I thought this would be categorized as a new bike, thus breaking the rule, he said no, because he was using all the old parts.

Somehow, to me the essence or soul of a bike is in the frame. So I still feel like this is a new bike.

I'm just curious about how other people define their bikes. Opinions?

And yes, this is completely random and frivolous. But hey, I think it's a fun thing to contemplate.

ETA - I completely stripped my road bike down to frame, fork, saddle and seatpost earlier this year and replaced everything else. To me, it's still the same bike, she just went on a serious weight loss program. But really... is she???