"Colourless is only what light can penetrate completely. A colour has its origin in the purely physical world. It originates in light rays being reflected from or penetrating a substance. The things we see get their colour and appearance from rays of light.The rays of light hit an object, are reflected by or penetrate it and are picked up by the eye, Some of them are absorbed by the object thus changing the intensity and composition of the reflecting or penetrating light."
"The perception of colour depends on the source of the light. The sun is our most important source of light. Daylight is rich in blue tones. In contrast the standard light bulb does not contain much blue or violet but has a great deal of yellow, orange and red. Sunlight has a more golden tone. When it falls on fresh snow it looks more yellowish while fresh ski tracks cast a blue shadow because of the pure light from the sky."
"Textiles seem to have different shades of colour by daylight and by lamplight. A scarlet material seem to be intensely red by lamplight and bluish in daylight. A blue-green material seems less blue by lamplight than daylight. When an object reflects more than 80-90% of the light falling on it we perceive it as white. When it absorbs more than 95% of the light it appears black."