good question
![Shocked :o](http://forum.outerra.com/Smileys/default/shocked.gif)
What if we put some entertainment?
The theory of color has its origin in the famous book of opticks (1704) by Isaac Netwon, but that is in constant review, since the primary colors in the theory of traditional color and modern theory disagree, where they speak between light and pigments Although this is another story.
The only thing we know is that in Japan their traffic lights do not have the green color (Midori). For them blue (ao) and green (Midori) is the same color.