Georges Seurat on Impressionism

“The purity of the spectral element being the keystone of my.. ..searching for an optical formula on this basis ever, since I held a brush.. ..having read Charles Blanc in school and therefore knowing Chevreul's laws and Eugene Delacroix's precepts, having read the studies by the same Charles Blanc on the same painter [= Delacroix] (if I remember correctly).”