The major significance of Newton's work is that it overturned the dogma, attributed to Aristotle or Theophrastus and accepted by scholars in Newton's time, that "pure" light (such as the light attributed to the Sun) is fundamentally white or colourless, and is altered into color by mixture with darkness caused by interactions with matter. Newton showed just the opposite was true: light is composed of different spectral hues (he describes seven — red, orange, yellow, green, blue, indigo and violet), and all colours, including white, are formed by various mixtures of these hues. He demonstrates that color arises from a physical property of light — each hue is refracted at a characteristic angle by a prism or lens — but he clearly states that color is a sensation within the mind and not an inherent property of material objects or of light itself. For example, he demonstrates that a red violet (magenta) color can be mixed by overlapping the red and violet ends of two spectra, although this color does not appear in the spectrum and therefore is not a "color of light". By connecting the red and violet ends of the spectrum, he organised all colours as a color circle that both quantitatively predicts color mixtures and qualitatively describes the perceived similarity among hues.