Was pi invented or discovered?

[Aractus]

""Red" is not an intrinsic property of light, it's merely a way for humans to describe how our eyes perceive certain wavelengths."

To which you replied,

"Actually, for us it is."
Which perfectly explains why it is not, in as little as two words no less. Impressive. The rest is unnecessary, and in truth, you now seem to have failed to disagree with me in any way (but seemed to feel compelled to disagree nevertheless).

Rhythm, I don't know what to tell you. Light has the property "wavelength". Retinas have three separate sensors for sensitivity which detect light as "RED", "GREEN" or "BLUE". Humans, (almost always men), can be born colour-blind where one or even two of those sensors don't work (or do not function well under daylight conditions). There are two types of light sensors in our retinas - rods and cones. Cones are the ones that detect COLOUR. They are the ones that cause us to know and appreciate what colour is. They are the ones that decide whether a certain wavelength is RED, GREEN or BLUE ... or a combination thereof. At night, and in the dark - when there is not a lot of light that comes through, the cones are mostly inactive and the rods are active. Rods do not respond to different colours, and thus we see a BLACK AND WHITE image in the dark. RED is a real, tangible thing - it is not a "perception". It is determined by the cones, we didn't invent it. We invented names for other colours like YELLOW which is not a "real, tangible" colour as far as our retinas are concerned, we see the world as "RED, GREEN, BLUE".