What was the philosophy behind the gothic use of light and color in cathedral design?

The philosophy behind the Gothic use of light and color in cathedral design because of practical and symbolical uses. Practically, most especially the areas in northern and western regions, they have this design because the area is cloudy that to the point of covering the light from the sun. The style attempted to maximize interior light. Symbolically, light and color is a channel to illuminate the soul and to reunite with god.

Ithink that'd be 4, sorry if i'm wrong.