Absence of light results in black. Cyan, magenta and yellow are the photographic primary colours and are used to create separations for photographic and ink colour printing. Subtractive Pigments combine in the subtractive system. Artists that work with physical media are concerned with the subtractive method since we work primarily in pigments. The visual appeal of colour colour has a basic, instinctive appeal to everyone.
Some artists use colour primarily as and emotional element and in an intuitive manner.
Other artists, like Josef Albers, have studied colour perception extensively and published seminal books that are still widely in use. There is no one consistent colour for any object. Grass may be gray at dawn, bright green at noon and nearly black at night. Monet's work may appear at first an arbitrary use of colour, but when we become aware of the time of day the painting was made, we realize that his work captures a fleeting sensation of light. Rarely do we see a colour by itself, usually it is in conjunction with other colours.