Opening keynote presentation at the 7th International Symbiosis Congress (Kraków, Poland, July 2012), which was dedicated to the memory of Lynn Margulis, outstanding scientist. It is particularly appropriate that this tribute appears in this journal based in Cracow, for shortly before her passing, she told me how very much she looked forward to coming to the Jagiellonian University in Cracow, “the great city of Copernicus”, as the invited keynote speaker to this Congress. DZ