He was on LSD.
Of course they just batted him off, saying "That's great John, we've got to get back to this meeting now." Or something along those lines (I forget which book I read this in, probably John Lennon: The New York Years by photographer Bob Gruen, but I'm not sure).
What if LSD is the real perception of reality?
Supposedly The Beatles argued about this often. My friend Mandy responded when I told her this idea by saying, "That sounds like something someone on LSD would say." Which is true. But what if it wasn't? What if the only way to actually see how the world is was by doing some drug invented in a lab in the 60s? Or any drug, or ANYTHING for that matter? What if we've been living in an altered sense of reality because we haven't found the right glasses to wear to see it properly?
What if the world is a movie in 3-D and we haven't found the glasses, so all we are seeing is a blurry image? Eventually we'd just think that blurry picture was how it was supposed to be.
Now, this probably all comes back to some Descartes thought about centuries ago. Descartes asked, "How do you know your not dreaming?" and through endless babbling and questions, he decided that they only way we know that we're not dreaming is because God wouldn't do that to us. But when you asked him, "How do you know God exists?" his answer was something along the lines of "Well, according to my definition of God being all-powerful, all-knowing, etc... that must include all-existing, and therefore he exists."
You might not think that makes any sense. And that's because it doesn't. It's called the Cartesian Circle, and philosophy professors will be debating about it for the next 2459 years.
So I guess we'll never know. I mean, how could you ever tell?
Maybe this was what John Lennon was getting at.
Or maybe he was just high.