Pencil drawing of Wilhelm Ostwald (1853-1933), German physical chemist and Nobel Laureate. Ostwald is considered one of the founders of modern physical chemistry. He was instrumental in identifying the proper action of catalysts. He stated that although the overall energy change of a reaction remained unaltered, the catalyst lowered the activation energy. This concept made catalysis useful in industry, and is the view still held today. As a result, Ostwald was awarded the 1909 Nobel Prize for Chemistry. He spent the rest of his life studying thermodynamics, colour theory and the philosophy of science.