"I’m working on a canvas of roses on bright green background and two canvases of large bouquets of violet Irises, one lot against a pink background in which the effect is harmonious and soft through the combination of greens, pinks, violets. On the contrary, the other violet bouquet (ranging up to pure carmine and Prussian blue) standing out against a striking lemon yellow background with other yellow tones in the vase and the base on which it rests is an effect of terribly disparate complementaries that reinforce each other by their opposition."
Letter (870) from: Vincent van Gogh
To: Theo van Gogh
Date: Saint-Rémy-de-Provence, Sunday, 11 May 1890