A century ago, Camillo Golgi and Santiago Santiago Ramón y Cajal were jointly awarded the Nobel Prize for medicine. Golgi (1873) devised a novel technique for staining nervous tissue; it consisted of hardening the preparation in potassium bichromate and then impregnating it with silver nitrate. The subsequent black reaction (reazione nera) exposed the networks of nerves in grey matter in a manner that had not been possible previously. By using this technique Santiago Ramón y Cajal carried out an extensive investigation of the structure of the nervous system laying down the foundation of modern neuroscience. This article explores the realtive contribution of the two great scientist to the progress of scientific knowledge in the turn between the 19th and 20th century.