What is the violin piece in the Human Footprint advert for Channel 4 called?

I was searching for this very question myself only yesterday, and i inadvertantly stumbled on it on my electic piano. in the book it's called 'prelude (wohltemperiert klavier I no.1) by js bach' , but if you do a search for "j s bach, prelude" I'm sure you'll find it. i found it on itunes, it's a cello, not violin.hope this helps.