Of all the subjects presented in this book, this part devoted to color theory might be the most perplexing one. Although a basic understanding of the color spectrum is rather easy to develop, color theory is an almost infinitely complex subject with roots in both science and art. It can therefore be a daunting task to learn about color composition in a way that is true to both art history and scientific truth, and I have seen many designers stumbling on the most basic of questions: Is yellow a primary color? Which color combinations are harmonic? What is the true complementary color to blue?

I hope that this chapter on the history of color theory can help answer some of these questions by highlighting both the mistakes and successes of key figures in the field. In this abbreviated and narrow introduction, I am especially interested in the conflict between the two distinct but related fields that both operate under the term ‘color theory’: Artistic color theory, which is concerned with the visual effects of color combination in the fine arts, and scientific color theory, which describes the nature of color through increasingly complex but precise color models. The following chapters will build on lessons learned in this chapter, and it is my belief that it is essential for designers to develop a solid understanding of this history in order to make good decisions about color.

One of the first known theories about color can be found in On Colors, a short text written in ancient Greece. The text was originally attributed to Aristotle, but it is now widely accepted to have been written by members of his Peripatetic school. Based on observations of how color behaves in nature, the text argues that all colors exist in a spectrum between darkness and light, and that four primary colors come from the four elements: fire, air, water, and earth. This can seem rather weird and speculative today, but these observations made sense at the time: A plant is green above ground and white in its roots, thus the color must come from the sun. Likewise, a plant left to dry will lose its vivid colors, thus water provides color too. This theory is typical of how color theorists for centuries used color to establish a general theory of the universe. Despite the erroneous theory, On Colors has a series of important observations, like the fact that “darkness is not a colour at all, but is merely an absence of light”1 – a discovery propelled by watching how clouds darken as they thicken2.

Like so many other areas of science, Isaac Newton completely redefined the conventional theories on the behavior of light when he published the first edition of Opticks in 1704. Rather than seeing light as a void of color, Newton discovered that white light is a combination of all colors across the color spectrum. The basics of his experiments was a well-known phenomena: When you shine white light through a prism, the light is split into colors from across the color spectrum. However, Newton discovered that he could recombine these spectral colors to once again turn them into white light.

Newton's color circle used seven colors mapped to a musical octave starting at the tone D.

Newton also discovered that if he blended the first color (red) and last color (violet) of the color spectrum, he could produce magenta, an extra-spectral color that does not exist in the rainbow. This prompted him to wrap the color spectrum into a circle, beginning a tradition of using basic shapes to represent the relationship between colors. Newton used a circle because it could be used to predict the result of color mixing for two colors by pointing to the color midway between these colors. The colors on Newton’s circle have asymmetric distances to each other because Newton wanted the circle to have seven colors – the exact number of days in a week and musical notes in an octave3.

While Newton was interested in a scientific explanation of color, the German poet Wolfgang von Goethe dedicated his book Theory of Colors from 1810 to a more human-centered analysis of the perception of color. Through a series of experiments that measured the eye’s response to certain colors, Goethe created what is arguably the most famous color circle of all time. The circle had three primary colors – magenta, yellow, and blue – which he believed could mix all other colors in the spectrum.

Goethe's color circle with magenta, yellow, and blue primary colors.

This publication was in many ways at odds with Newton’s theories, as Goethe believed that the prism, not the light, was responsible for the creation of color, and that darkness was not an absence of light. Although Newton eventually won the argument about the nature of light, Goethe’s work is important to us because it focuses on the cognitive effect that color has on humans. His research on the effects of after-images and optical illusions is especially interesting, because it points towards the later works of Johannes Itten and Josef Albers4.

Even though Newton's and Goethe’s color circles may seem to be at odds with each other, they are in some way both correct as they illustrate the behavior of color in different material. Newton describes how his spectral colors can mix most visible colors including white, and this is true because light mixes in an additive way: Combining lights of different colors will eventually result in white light. Goethe describes how his three primary colors can mix most visible colors including black, and this is true because pigments mix in a subtractive way: Combining paints of different colors will eventually result in black paint by subtracting waves of light.

RGB in additive color mixing.

CMY in subtractive color mixing.

In a quest to create a unified notation for color – like we know it from musical notation – artists soon started depicting the color spectrum as 3D solids. A concurrent example of this can be found in Tobias Mayer’s color triangle from his book The Affinity of Color Commentary, published posthumously in 1775. Mayer sought to accurately define the number of individual colors the human eye can see, and this required him to add another dimension to represent the variations of brightness for each color. Mayer painted the corners of a triangle with the three traditional primary colors from painting – red, yellow, and blue – and connected the corners by mixing the opposing colors together. Unlike the traditional color circle, he created many variations of this triangle by stacking triangles of different brightnesses on top of each other. This made it possible to define a color by its position within a 3D space, a technique still used to this day. Mayer ultimately failed at creating a color model with perceptually uniform steps, as he did not understand the irregularities of the human eye5.

Tobias Mayer's color triangles.

The German painter Philipp Otto Runge took this same approach when creating his spherical representation of the color spectrum, published in his Color Sphere manuscript in 1810. Runge’s sphere had white and black poles with colored bands running between them. However, like many other representations of color before it, the model did not differentiate between brightness and saturation, which meant that the resulting model had little variation in color intensity. This sphere had the same problem as Mayer’s triangle, as the steps were not perceptually uniform6.