Isaac Newton is the most famous answer to this question, and the one most likely behind it if you encountered it in a quiz or classroom. In 1666, Newton used a glass prism to split sunlight into a rainbow of colors, proving that white light is actually a mixture of every color in the visible spectrum. He identified seven distinct colors: red, orange, yellow, green, blue, indigo, and violet. But Newton was far from alone. The science of color has captivated thinkers for more than two thousand years, from ancient Greek philosophers to modern neuroscientists.
Isaac Newton and the Prism Experiment
Newton’s breakthrough was showing that color isn’t something added to light. It’s already inside it. By passing a narrow beam of sunlight through a triangular glass prism, he spread it into a band of colors, then used a second prism to recombine them back into white light. This proved that the prism wasn’t creating color; it was revealing what was already there. Newton published his findings in Opticks in 1704, writing: “if the Sun’s Light consisted of but one sort of Rays, there would be but one Colour in the whole World.”
His work established the physical foundation for color science. Every screen you look at today, every printed image, every discussion of wavelengths and spectra traces back to Newton’s realization that white light is composite.
Aristotle’s Earlier Theory
Long before Newton, Aristotle proposed his own ideas about color in a treatise called On Colors. He linked colors to the classical elements. Fire and the sun were golden, air and water were naturally white, and earth appeared white in its pure form but took on other colors when “dyed” by moisture or other substances. As evidence, he pointed to ashes: they turn white when moisture is burned away, but darken when stained by smoke. His framework was wrong in physical terms, but it represented one of the first systematic attempts to explain why the world looks the way it does.
Goethe’s Challenge to Newton
In 1810, the German writer Johann Wolfgang von Goethe published Theory of Colours, a direct challenge to Newton’s physics. Goethe wasn’t primarily interested in what light does when it passes through glass. He was fascinated by what happens when light reaches a human eye and brain. His work focused on color perception: why colors look different next to each other, how shadows can appear tinted, and how our emotional responses to color shape what we actually see.
Scientists largely dismissed his physics, and rightly so. But as one translator noted, that dismissal caused “a well-arranged mass of observations and experiments, many of which are important and interesting” to be overlooked. Goethe’s attention to the subjective, psychological side of color proved deeply influential for artists and philosophers. His core insight, that color isn’t just a property of light but also a product of human perception, remains central to how designers and artists think about color today.
Young, Helmholtz, and How Eyes See Color
In the early 1800s, Thomas Young proposed that the human eye doesn’t need a separate receptor for every possible color. Instead, he suggested three types of light-sensitive cells, each tuned to a different range of wavelengths. Hermann von Helmholtz refined this idea decades later into what became known as the trichromatic theory: your eye contains three kinds of cone cells, sensitive to red, green, and blue light. Every color you perceive is your brain’s interpretation of the signals from these three receptor types mixed together in different proportions.
This theory turned out to be correct and explains why about 4.4% of males and 0.6% of females worldwide have some form of color vision deficiency. The most common type involves the green-sensitive cones, affecting roughly 3.7% of males. When one cone type doesn’t function normally, the brain loses part of its ability to distinguish certain colors.
Maxwell’s First Color Photograph
James Clerk Maxwell, best known for his equations describing electromagnetism, put trichromatic theory to a dramatic practical test in 1861. He photographed a tartan ribbon three separate times, once through a red filter, once through green, and once through blue-violet. He then projected all three images onto the same screen simultaneously, each through its matching filter. The overlapping projections produced a full-color image, the first color photograph ever made.
Maxwell himself acknowledged the results were imperfect. He noted the need for photographic materials more sensitive to red and green light. But the demonstration proved a powerful principle: you can recreate the full range of visible color by combining just three primary colors. This is exactly how your phone screen, television, and computer monitor work today, mixing red, green, and blue light at each pixel.
Munsell’s System for Describing Color
By the early 1900s, scientists and artists could explain and photograph color, but they still lacked a reliable way to talk about it. If you asked ten people to mix “sky blue,” you’d get ten different results. Albert Munsell, an American painter and art professor, set out to fix this. In 1905, he created a system that describes any color using three dimensions: hue (the basic color family, like red or blue-green), value (how light or dark it is, on a scale from 0 for pure black to 10 for pure white), and chroma (how vivid or muted it is, measured outward from neutral gray).
The Munsell system is still used today in soil science, dentistry, food science, and any field where people need to communicate about color precisely. It’s elegant because it matches how color actually behaves. A deep red can reach a chroma of 14, meaning it can be extremely vivid, while a yellow at the same darkness level tops out at a chroma of 6. The system captures these real-world asymmetries instead of forcing colors into a neat, uniform grid.
From Pantone to the Modern Era
The challenge of standardizing color reached the printing industry in the 1960s. Lawrence Herbert, a young employee at a printing company, grew frustrated with how difficult it was to get consistent color results across different presses and inks. His solution was the Pantone Matching System, introduced in 1963, which assigned a unique number to each of thousands of specific ink formulations. For the first time, a designer in New York and a printer in Tokyo could reference the same number and produce the same color.
Today, color science has moved into the brain itself. Neuroscientists study how different areas of the visual cortex process color information. Research shows that the earliest visual processing areas respond strongly to how saturated a color is, while areas further along the visual pathway handle more complex tasks like recognizing objects by their color. The question that fascinated Newton, “what is color, really?” continues to pull researchers deeper into the intersection of physics, biology, and perception.