I have a guitar. One day I decide to replace the tuners. Some time later, I replace the pickups and electrics. Six months later I replace the pickguard. Then the following year I replace the bridge. After all this time, the neck is a bit warped so I fit a new one. And the body's looking a bit sorry for itself, so... I carry on this way for some time until one day I realise that I've replaced every part of the guitar. So is it still the same guitar, or a completely different one? And at which point did it cease being the old guitar and start being the new one?