Le Corbusier designed two color collections for the wallpaper company Salubra: the "Clavier de couleurs" from 1931 with 43 shades and the collection from 1959 with 20 colors. However, he did not settle for simply choosing 43 shades based on his experience as an architect and painter; he organized the tones into 12 sample cards, allowing three to five colors to be isolated or combined using a slider. Each of these cards featured a distinct color mood intended to evoke a specific spatial effect in application. This not only created a useful tool but also resulted in a kind of testament to purist color theory: an indispensable foundation and a valuable working instrument for anyone engaged with color in theory and practice. Le Corbusier specialist Arthur Rüegg explains the significance.