Things that never occurred to me #1 in a series

I was listening to a podcast today and they mentioned something that made me go huh!

Colours. We all know what they are,and can name many of them.

But what they said was that colors are a function of the brain. Our brain interprets what we see and we identify it as e.g. Red.

However there is no way of knowing, or indeed comparing what I consider to be red, with what you consider to be red. I know that you see red and I see red, but there is no way to tell if we see the same red.

We can identify by pointing a colour swatch what we see as red, or blue or green, and you can do the same. We both point at the same "red", and we agree and we carry on. Red is red is red, by popular decision.

It just made me go huh is all, and I wonder what else it is that is obvious when someone mentions it?