During the 19th century, scientist-writers such as Michel Eugène Chevreul, Ogden Rood and David Sutter wrote treatises on color, optical effects and perception.
They adapted the scientific research of Hermann von Helmholtz and Isaac Newton into a form accessible to laypeople.
Artists followed new discoveries in perception with great interest.

Chevreul was perhaps the most important influence on artists at the time; his great contribution was producing a color wheel of primary and intermediary hues.
Chevreul was a French chemist who restored tapestries.
During his restorations he noticed that the only way to restore a section properly was to take into account the influence of the colors around the missing wool; he could not produce the right hue unless he recognized the surrounding dyes.
Chevreul discovered that two colors juxtaposed, slightly overlapping or very close together, would have the effect of another color when seen from a distance.
The discovery of this phenomenon became the basis for the pointillist technique of the Neoimpressionist painters.

Chevreul also realized that the "halo" that one sees after looking at a color is the opposing color (also known as complementary color).
For example: After looking at a red object, one may see a cyan echo/halo of the original object.
This complementary color (as an example, cyan for red) is due to retinal persistence.
Neoimpressionist painters interested in the interplay of colors made extensive use of complementary colors in their paintings.
In his works, Chevreul advised artists to think and paint not just the color of the central object, but to add colors and make appropriate adjustments to achieve a harmony among colors.
It seems that the harmony Chevreul wrote about is what Seurat came to call "emotion".

It is not clear whether Seurat read all of Chevreul's book on color contrast, published in 1859, but he did copy out several paragraphs from the chapter on painting, and he had read Charles Blanc's Grammaire des arts du dessin (1867), which cites Chevreul's work.
Blanc's book was directed at artists and art connoisseurs.
Because of color's emotional significance to him, he made explicit recommendations that were close to the theories later adopted by the Neoimpressionists.
He said that color should not be based on the "judgment of taste", but rather it should be close to what we experience in reality.
Blanc did not want artists to use equal intensities of color, but to consciously plan and understand the role of each hue in creating a whole.

While Chevreul based his theories on Newton's thoughts on the mixing of light, Ogden Rood based his writings on the work of Helmholtz.
He analyzed the effects of mixing and juxtaposing material pigments.
Rood valued as primary colors red, green, and blue-violet.
Like Chevreul, he said that if two colors are placed next to each other, from a distance they look like a third distinctive color.
He also pointed out that the juxtaposition of primary hues next to each other would create a far more intense and pleasing color, when perceived by the eye and mind, than the corresponding color made simply by mixing paint.
Rood advised artists to be aware of the difference between additive and subtractive qualities of color, since material pigments and optical pigments (light) do not mix in the same way:
Material pigments: Red + Yellow + Blue = Black
Optical / Light : Red + Green + Blue = White
Seurat was also influenced by Sutter's Phenomena of Vision (1880), in which he wrote that "the laws of harmony can be learned as one learns the laws of harmony and music".
He heard lectures in the 1880s by the mathematician Charles Henry at the Sorbonne, who discussed the emotional properties and symbolic meaning of lines and color.
There remains controversy over the extent to which Henry's ideas were adopted by Seurat.
During the 19th century, scientist-writers such as Michel Eugène Chevreul, Ogden Rood and David Sutter wrote treatises on color, optical effects and perception. They adapted the scientific research of Hermann von Helmholtz and Isaac Newton into a form accessible to laypeople. Artists followed new discoveries in perception with great interest.
Chevreul was perhaps the most important influence on artists at the time; his great contribution was producing a color wheel of primary and intermediary hues. Chevreul was a French chemist who restored tapestries. During his restorations he noticed that the only way to restore a section properly was to take into account the influence of the colors around the missing wool; he could not produce the right hue unless he recognized the surrounding dyes. Chevreul discovered that two colors juxtaposed, slightly overlapping or very close together, would have the effect of another color when seen from a distance. The discovery of this phenomenon became the basis for the pointillist technique of the Neoimpressionist painters.
Chevreul also realized that the "halo" that one sees after looking at a color is the opposing color (also known as complementary color). For example: After looking at a red object, one may see a cyan echo/halo of the original object. This complementary color (as an example, cyan for red) is due to retinal persistence. Neoimpressionist painters interested in the interplay of colors made extensive use of complementary colors in their paintings. In his works, Chevreul advised artists to think and paint not just the color of the central object, but to add colors and make appropriate adjustments to achieve a harmony among colors. It seems that the harmony Chevreul wrote about is what Seurat came to call "emotion".
It is not clear whether Seurat read all of Chevreul's book on color contrast, published in 1859, but he did copy out several paragraphs from the chapter on painting, and he had read Charles Blanc's Grammaire des arts du dessin (1867), which cites Chevreul's work. Blanc's book was directed at artists and art connoisseurs. Because of color's emotional significance to him, he made explicit recommendations that were close to the theories later adopted by the Neoimpressionists. He said that color should not be based on the "judgment of taste", but rather it should be close to what we experience in reality. Blanc did not want artists to use equal intensities of color, but to consciously plan and understand the role of each hue in creating a whole.
While Chevreul based his theories on Newton's thoughts on the mixing of light, Ogden Rood based his writings on the work of Helmholtz. He analyzed the effects of mixing and juxtaposing material pigments. Rood valued as primary colors red, green, and blue-violet. Like Chevreul, he said that if two colors are placed next to each other, from a distance they look like a third distinctive color. He also pointed out that the juxtaposition of primary hues next to each other would create a far more intense and pleasing color, when perceived by the eye and mind, than the corresponding color made simply by mixing paint. Rood advised artists to be aware of the difference between additive and subtractive qualities of color, since material pigments and optical pigments (light) do not mix in the same way:
Material pigments: Red + Yellow + Blue = Black
Optical / Light : Red + Green + Blue = White
Seurat was also influenced by Sutter's Phenomena of Vision (1880), in which he wrote that "the laws of harmony can be learned as one learns the laws of harmony and music". He heard lectures in the 1880s by the mathematician Charles Henry at the Sorbonne, who discussed the emotional properties and symbolic meaning of lines and color. There remains controversy over the extent to which Henry's ideas were adopted by Seurat.
Georges Seurat