Throughout most of my youth, the word was that there would be nine episodes, of which IV through VI were the "middle" trilogy. This was not the original line. Star Wars was originally a standalone flick. There was eventually a trilogy, but just to fuck with us, Lucas decided that they were episodes IV through VI. The subtitle "A New Hope" suggested that things were turning around, and this fit in with the idea that it was all part of a much larger story. By the early 80's, it was common knowledge that there would ultimately be nine movies. That's what Lucas had said. Then after he finally made the prequel trilogy, he changed his tune and said that that was it. He even implied that that's how it's always been, despite the fact that many people remember hearing that there would eventually be nine, not just six.
So... with Star Wars, what people have "always" said and/or "always" believed depends on when you asked them. The story and overall vision has changed at least twice.