Essentially only one thing in life interests us: our psychical constitution, the mechanism of which was and is wrapped in darkness. All human resources, art, religion, literature, philosophy and historical sciences, all of them join in bringing light in this darkness.

Nobel Lectures, Physiology or Medicine 1901-1921, Nobel lecture for award received in 1904, Physiology of Digestion (pp. 154—155), Elsevier Publishing Company. Amsterdam, Netherlands. 1967