The most mind-blowing load of nonsense ever.

If I can only define reality from my experience, and you can only from yours. and (as far as I know) the sky is blue, and we agree the sky is blue, but what I know as blue you know as green, and what I know as green you know as blue, so we agree that the sky is blue. but for you, the sky is actually green and to me, it's actually blue.

so then, how do I know that, to you, I am not a cat? maybe what you define as "human" I define as "cat" but we verbally define it the same. even though we experience it in a deferent way.
of course that's all a load of non-sense. but it's mind blowing nonsense.