Jules Bordet, a pioneering immunologist, lived until the dawn of molecular immunology. He was born in Belgium in 1870, obtained a medical degree in 1892, worked at l'Institut Pasteur in Paris from 1894 to 1901 and then established the Pasteur Institute of Brabant in Brussels. Before World War I, Bordet found that complement binds to antibody-antigen complexes regardless of the antigen or antibodies involved. Subsequently he developed the complement fixation test that was of diagnostic importance for several decades. For his research concerning complement he was awarded the 1919 Nobel Prize in Physiology or Medicine. During that period he also discovered anaphylatoxin, conglutinin, and the cause of whooping cough (Bordetella pertussis). After World War I he found how thrombin forms, how platelets participate in clotting, lysozyme in human milk and much of the biology of bacteriophages. In addition, Bordet worked fervently to limit weapons of mass destruction and promote peace until his death in 1961.