As I am walking around the Croatian capital and looking at people walking past, I start thinking about history. Ancient history, that is. I think of Africa. I think of the Middle East. I think of Persia. I think of India and China. I think of Egypt. I think of Greece. I think of Rome. I think of Germany. I think of Venice. I think of Spain and Portugal. I think of France. I think of Holland. I think of Britain. I think of America. And then I think of India and China again. I think of the Middle East. A circle. A circular epidemic. Yes, a disease circling the planet over and over again. It takes me only a short while to sum it all up: the origin and spread of the human species. The migrations. The civilizations. The conquests. The rises and falls. The perpetual circle. The unending epidemic. By and by, I become despondent. But a happy end presents itself at last: the Petri dish! No matter what, the planet is limited in size. The epidemic will thus meet its end sooner or later. The disease will perish. And the circle will be closed for good. Alleluia!

To Julius Richard Petri