Colour Wheel Violet
Sir Isaac Newton (1643-1727) added violet to the prismatic spectrum in the 17th century, as part of a colour circle. The Expressionist painter and colour theorist Johannes Itten (1888-1967) combined the concept of a colour wheel containing pairs of complementary colours, with the physical concept of the prismatic spectrum. He defined violet within his colour circle, although Itten's choice of colour has been criticised for not being exact.
Itten described yellow and violet as a light-dark contrast.