[Harp-L] What is a key?

[Michael Rubin <rubinmichael@xxxxxxxxxxxxx>]

I have been playing harp 21 years.  I make my living teaching and playing.  Often I teach absolute beginners.  Explaining what a key is is very difficult for me.  
   
  I often compare a key to a person's aura.  The note that has the same name as the key pervades the entire song.
   
  I often will teach them how to create all 12 major scales then explain how all the notes in the major scales show up in either the I, IV or V chord..  
   
  I will teach them the C major scale on a C diatonic in the middle octave where no bending is required and then play a rhythm in the key of C for them to play over.  Then I will play the same rhythm in the key of C#.  They can hear how playing on key  sounds compared to playing off key.
   
  I talk about the tonic being the tonal center of the song and all notes having a relationship to that center and how interval distances are easier to recognize that note name unless on has perfect pitch.  I compare the tonic to the ground floor and the interval to rungs on a ladder.  
   
  I do all kinds of stuff.  Yet the question remains:
  WHAT IS A KEY?
  Thank you,
  Michael Rubin
  Michaelrubinharmonica.com