A horse is a horse, of course, of course

can anyone tell me where this line comes from? "a horse is a horse, of course, of course". any sort of refference will do...thanks, this is a really fun site, btw :)
oh, another question. when someone says "the house votes for one party over the other" what do they mean? what house?
thanx again!
Corina

This is a line from the theme song for the television program, Mr. Ed, who just happened to be a talking horse.

"A horse is a horse, of course, of course,
And no one can talk to a horse, of course,
Unless, of course, the horse, of course,
Is the famous Mr. Ed!"