White, purity, renewal, clean, brilliance, calm..etc..etc..
Using the white paper can often be difficult and my early
forays into painting with watercolors left my paper "muddily"
covered from side to side and corner to corner, barely showing
any of the beautiful white paper. I've since learned my lesson
(or at least one of them) to leave the sparkle of the white paper
showing through..I think it adds so much to a painting.