As the origins of life and the eye are ocean-based, it makes sense that the properties of the human eye ("why we see what we see") were largely evolved to perform specific tasks suitable for water. The fact that we can only observe a limited range of the electromagnetic spectrum—the part that water doesn't filter out—being a good example.

However, is the fact that we perceive water as being "clear" important? Is our optic system calibrated to see clean water as "clear". Obviously there are many things to factor in here: what the eye receives, how the brain perceives colour, even how we sociologically define colours, but water having "no colour" and not causing alarm or distress, for whatever reason would seem to be a good default for the whole thing.

Does anyone have any thoughts on this?

Hi, I've found some info about the color change of black tea based on acidity, but I would like to get some concrete answers and maybe pics of the polyphenols and tannins that are responsible for the "black" of black tea :) I'm a Chemistry student, so don't spare the details :)

Do we all perceive color the same way ? for example do we all see the same color green or is the word green or red or blue just names to tag how we perceive those color. If I switched eyes with someone he might see the grass the same way as I perceive the sky but still call it green even though for me it would be blue.

The same goes for colorblind people (those unfortunate to mix up colors) if they were brought up seeing the grass as we would see it red. He would say green to everything red if we were able to see through his eyes. It would rely on education then.

Do I make sense ?