In this seminal study, John Gage considers every conceivable aspect of colour in a groundbreaking analysis of the subject. He describes the first three theories of colour, articulated by philosophers from Democritus to Aristotle, as well as attempts to organize it or endow it with symbolic power. He unfolds its religious significance, as an incarnation of the Divine Light in the mosaics and stained glass of Byzantine and medieval Christianity, and its use in heraldry, as part of a language of coded signs. He shows how the rainbow gave up its secrets and how Renaissance artists approached colour with the help of the alchemists. He explores the analysis of the spectrum undertaken by Newton and continued by artists such as Seurat, and the use of the artists palette as an evolving scale of tones. He traces the influence of Goethes colour theory and developments as diverse as Matisses exploration of complementary shades and the manufacture of paints; and considers the theories and practices that attempted to unite colour and music, or make colour into a language of its own. Unfamiliar texts from all periods are featured, from the treatise that inspired Van Gogh to physicians scales of hair and urine colours, and fresh light is thrown on the hidden meanings of many familiar masterpieces.