[hb]

I'm trying to grasp the circle of fifths and it's relationship to friendly chords but I can't seem to grasp one thing.....How can one chord (or should I say "scale") like the the 'C' , have exactly the same notes as the 'A minor"? I know a C scale starts on a C and an A scale starts on the A but in between they're the same. How can this be?
thanks,
hb