The term invented by Robert Delaunay to describe the abstract painting developed by him and his wife Sonia Delaunay from about 1910. Their work was also named Orphism by the poet and critic Apollinaire. The term is derived from the theories of M-E Chevreul whose book of colour theory De la loi du contraste simultanée des couleurs (On the law of the simultaneous contrast of colours) was published in Paris in 1839. It had an increasing impact on French painters from then on, particularly the Impressionists and Post-Impressionists generally, and especially the Neo-Impressionists. The Delaunays' paintings consisted of interlocking or overlapping patches, or planes, of contrasting (or complementary) colours. In Chevreul's theory, and in reality, contrasting colours brought together (i. E. Simultaneous) enhance each other, giving the painting greater intensity and vibrance of colour. The compositions were initially derived from architecture (e. G. R Delaunay's Windows series) but by 1912 he had begun to make paintings in totally abstract circular formats (Disques and Formes circulaires cosmiques series). These compositions were still ultimately based on nature however. In 1912 Delaunay wrote: 'Direct observation of the luminous essence of nature is for me indispensable'.