the nineteenth century that Justus von Liebig in Germany discovered that plants feed on nitrogen compounds and carbon dioxide derived from the air, as well as minerals in the soil. He then invented nitrogen-based fertilizer. Nearly a century later, M?ller (1939; http://www.britannica.com/eb/article-9054225) tested a compound, dichlorodiphenyltrichloroethane (DDT) and found it as an 'ideal' insecticide. The German chemist Othmar Zeidler had first synthesized this compound in 1874, but had failed to realize its value as an insecticide. Then, a