system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does white light contain all colors of the spectrum, but when you combine every color you get black?
gpt
Pigment is subtractive, in that when you add pigment together, you subtract the wavelengths of light that can be reflected. At some point, you add enough pigment together that you have subtracted every wavelength of light as it hits the combination of pigment, so what you see is black (obviously you aren't absorbing 100% of visible light with the tech we have right now, but enough that there is no color to be identified so you end up with what we call black).  

Light is additive in that as you add visible light waves together they approach what we call white - the presence of all visible light waves.