Our investigation was guided by our prior experience with the Ag polymorphism. In preparing this "history" of the discovery of Au, I constructed an outline based on a hypothetico-deductive structure, showing the actual events which led to the discovery of the association of Au with hepatitis. From this it is clear that I could not have planned the investigation at its beginning to find the cause of hepatitis B. This experience does not encourage an approach to basic research which is based exclusively on specific-goal directed programs for the solution of biological problems. The next step was to collect information on the distribution of Au and anti-Au in different human populations and disease groups. We had established a collection of serum and plasma samples, later to develop into the Blood Collection of the Division of Clinical Research of The Institute for Cancer Research (now The Fox Chase Cancer Center) which now numbers more than 200,000 specimens. The antigen was very stable; blood which had been frozen and stored for 10 years or more still gave strong reactions for Au. Presence or absence of Au appeared, at least in the early experiments, to be an inherent characteristic of an individual.