Undoubtedly, the most referenced colour in the history of art has been the colour blue; it is perhaps also the most magnificent. From its invention by the ancient Egyptians, to the painted parchment in medieval Psalters, through Renaissance brocades and vast perspectival grids defined by winsome skies to those manufactured by James Turrell via artificial light or real ones enhanced and framed like sculptures, blue has the undeniable lure and power of a paradoxical emotion: to excite yet appease.