What makes D, D?

[Saaa]

> That is a question for a philosopher, right up there with what makes you,
> you? IIRC the body replaces 100% of it's matter several times of your 
> life. Some parts more often than others.
No, some parts stay with you for the rest of your life (e.g. nuclear pore 
scaffold in brain cells)
What could it be if it's not the matter ..
Related old meme: We only use 10% of our brain capacity