The XII Max Born Symposium has a special character. It was held in honour th of Jan Lopusza nski on the occasion of his 75 birthday. As a rule the Max Born Symposia organized by the Institute of Theoretical Physics at the University of Wroc law were devoted to well-de ned subjects of contemporary interest. This time, however, the organizers decided to make an exception. Lopusza nski's in?uence on and contribution to the development of th- retical physics at Wrocla w University is highly appreciable. His personality and scienti c achievements gave him authority which he used to the best -...