Why is white paper "white" and not black I understand this may seem a silly question but I really would like to know. As far as I understand it (may be wrong) additive colours (visible wavelengths) when combined equally produce white. Subtractive colours, when all the colours are equally combined produce black. Additive colours are produced by a light source. Subtractive colours are produced by a non-light source (e.g. reflection, filter, lens, etc). So, if I look at a piece of white paper I am seeing all the colours (with none absorbed)combined so why does it appear white and not black, as all the colours are being reflected equally.