The Colour Blue

Blue. The colour blue. Blue paint. An intelligent shade of blue. Blue.
I once was talking to someone about perception.(more than once actually) I said something to the effect of, "What if what you see as green, someone else sees as blue, so when you say green, they think of what you call blue but what they call green? There would be no way of realizing that the perception is mixed up. You and this other person would each be seeing two different colours, but would think you’re seeing the same."
The reply I would get was something like, "But they could figure it out by comparing that colour to other colours, noticing that it has different properties."
I don't really know about that, and I haven’t thought a whole lot on it. I won't bother to explain how that could work with shades and tones and things, but instead, I'll ask another question. What if someone perceived all colours differently from another, with a whole rotation of the colour wheel?
On a 180 degree rotation, when one sees blue, the other see's yellow; and when one sees red the other sees green. There would truly be no way for the two people to realize that they are seeing two different things. Colours would still follow all the same rules of mixing and shades and tones and colour wheel rotation, but each person would see different things.

Now sure, maybe an inspection of the brain at some time could reveal somehow that when one person's brain is stimulated in a certain area by a certain light wavelength, another person’s brain is stimulated in another area by the same light wavelength, and when you give each the opposite colour they trade which part is stimulated, but this doesn't really prove anything.
Perhaps one person's mind registers blue in one part of the brain and yellow in another; while another person registers blue in the part that the first registers yellow in, and registers yellow in what is the other's blue area. We would still not have any way of knowing if the two people are actually perceiving the same colours or different colours. We may be able to read brains, but we cannot read minds.
So what you see to be blue, another looks at and sees what you would call yellow, but still calls it blue. Who is really right? Maybe blue is actually the name for what you perceive as yellow. I don't really think either one is right or wrong. They are both seeing two different things, each as true as their own sight and no truer.
I could go on about this, and explain how about a 90 degree rotation one way would make blue equal to red, and the other way blue would be green, but a lesser rotation could make blue be purple or aqua, or a greater rotation make it another shade of green or some sort of orange. (all depending on exactly how you rotate) I could also talk about altering shade and tone. Instead though, I have something more interesting to say.
What if one person perceives blue as a duck and nobody realizes the discrepancy?
"Impossible!" some might think. "Such a misunderstanding would surely be noticed."
Well blue could very well be a duck, and steak might be the ocean. What if everything we see is only a manifestation of a concept?
What if you perceive life to involve these bipedal, upright walking, approximately vertically symmetrical beings called humans, but it's only a symbol created by your mind to make order out of things.
You might wonder: if you're the only one who sees "humans", than how can I, and for that matter everybody else, describe them. The answer is: I don't. I described my perception of the same concept in my own words. You see your version of my words at the other end, and taking that information, automatically translate it into the way you perceive it, so that you think I described something you’re familiar with (which I did, but not in a familiar way)
This is a challenging concept to explain, so I think I'll use a short story to clarify what I'm trying to say.

Bob and Ed were walking along down the street one day, according to Bob's perception. According to Ed's perception though, they were dripping sideways across a vertical incline with a bluish colour to it. Bob said to Ed, "You hungry? There's a Deli up ahead where we could get something."
Ed's perception of this was that Bob started bubbling, and little bits of colours shot up in a certain pattern that meant that they should go mix with some sustaining energy that was glowing on the vertical incline up ahead of where they were going. It was a common friendly symbiotic event. Ed responded by spitting up his own pattern of colours. This meant to Ed that he was informing Bob (Who Ed did not call Bob, but rather called a bluish green with a slight red glow) that though his energies were depleting he did not have the courage to fight off the pointy sticks guarding the energy.
Bob perceived this in the form of the words, "A sandwich would be good, but I haven’t got any money." So Bob told Ed that he'd be happy to pay for it.
Ed perceived this as a great display of colorful sparks shooting out of Bob like fireworks, declaring that the sticks were no match for him, and that he'd gladly help Ed get past them to reach the sustaining energy.
Shortly thereafter Bob and Ed went into the sandwich shop, ordered their sandwiches, (Bob paid) and sat down to eat.
Ed perceived a mighty and most epic battle with the evil sticks (Which sticks Bob perceives as part of economy by the way) in which Bob showed his great heroic might. They forced their way past and managed to assimilate some sustaining energy into themselves. It was an average chapter in an average book. Defeating sticks and assimilating energy.
Bob thought the sandwiches tasted good. Ed thought the energy played a very nice symphony inside of him.

Hopefully that helped to clarify things. Basically I'm saying, what if the way we perceive everything is only a manifestation, a representation, a symbol for the same concepts. We each perceive different symbols for the things in our life, and everything translates over from one to the other.
I can guess that I've left a lot of questions unanswered, but I think I've gotten a good start just the same. One question people might ask is, "Why does it matter?"
They might ask that. I might give them a clear answer too.
Anyway, I was thinking, people sure do have a lot of faith in their perception of things. Faith in their eyes and ears and thoughts. A lot of people seem to follow their eyes with a blind religious devotion. I find that interesting.
Well, if green were a conclusion and blue were green, then it's about now that I might say, "Blue." Anyone who thinks that what I call blue is a conclusion though, may well not see blue when I read this, so I ought to write a conclusion so that when they read it they can have the satisfaction of perceiving the colour blue.
I could conclude like Forrest Gump and say, "That's all I have to say about that." but the fact is that's not all that I have to say about that. Instead I'll conclude by saying, "That's all I now say about that." Blue enough?