This post reflects a previous one here.
Color (or colour) is both subjective and objective. Objectively, the rays of color light from a glass prism are different wavelengths (or frequencies) of light. The colors we see are those that reflect from objects; the others are absorbed. Colors are additive. Primary colors are red, green, blue; secondary colors are cyan, magenta, yellow.
But wavelengths go beyond the visible spectrum. Color is a visual phenomenon so human perceptions are what makes the different colors.
People perceive different colors differently. This is part cultural, part individual. Color symbolism varies over the world. See here. Pigment colors are subtractive. See here. Primary colors are cyan, magenta, yellow; secondary colors are red, green, blue.
Color is both subjective and objective. It has a subjective side and an objective side. There is a color duality.
The arts and the sciences form a duality. The arts are (ultimately) subjective. The sciences are (ultimately) objective. Style and taste are important in the arts but not in the sciences. Standards and measurements are important in the sciences but not in the arts.
Communication is a duality of subjectivity and objectivity. A subject expresses themselves but only subjectively unless they attend to the meanings of words and sentences so that others can objectively understand.
The arts have forms and expectations to facilitate communication while emphasizing the subjective. The sciences allow flexibility for subjects to express the objective content of their work.
History is an art because it expresses a narrative that emphasizes some people and events over other people and events. Science avoids giving undo emphasis to anything other than the elements of a science. Science and history are a duality.
Dualities are not dualisms. A dualism divides reality into two separate classes. Dualities distinguish two but do not see them as conflicting. Dualities combine two into one.