I don't think anybody knows. It all lines up on the bwps though.
I'm in Great shape is about the earth (living on the earth, farm houses, etc.)
I wanna be around is about procreation, a very earth thing

Woodshop is very earthy, building things, repairing her heart, whatever. Hammers, saws, wood
Vegatables grow in the earth.
On a Holiday is wind, the song starts with woodwinds, has slide whistles, etc.
Wind-chimes is obviously wind
Mrs. Oleary's Cow obviously fire
In Blue Hawaii obviously water
Good Vibrations represents the Aether.
Good link
http://www.mountainman.com.au/aeon_faq.htm