A Whiter Shade of Pale - Procol Harum

Does anyone know what this song means? Any guesses?

We skipped the light fandango
Turned cartwheels cross the floor
I was feeling kinda seasick
But the crowd called out for more
The room was humming harder
As the ceiling flew away
When we called out for another drink
The waiter brought a tray

And so it was that later
As the miller told his tale
That her face, at first just ghostly,
Turned a whiter shade of pale
She said, there is no reason
And the truth is plain to see.
But I wandered through my playing cards
And would not let her be
One of sixteen vestal virgins
Who were leaving for the coast
And although my eyes were open
They might have just as wellve been closed
She said, Im home on shore leave,
Though in truth we were at sea
So I took her by the looking glass
And forced her to agree
Saying, you must be the mermaid
Who took neptune for a ride.
But she smiled at me so sadly
That my anger straightway died

If music be the food of love
Then laughter is its queen
And likewise if behind is in front
Then dirt in truth is clean
My mouth by then like cardboard
Seemed to slip straight through my head
So we crash-dived straightway quickly
And attacked the ocean bed.