The history of the Doppler Principle discovery and its key role in many areas of physics, astronomy and technology is discussed. Despite the lack of theoretical and experimental evidence, Doppler thanks to his enthusiasm and intuition reached his goal to become the benefactor of mankind, though posthumously. Many following physicists further developed and applied his ideas. In fact, Doppler’s discovery was the most important physical result in our country during the 19th century. Faculty of Nuclear Sciences and Physical Engineering of the Czech Technical University borrowed Doppler’s name when organizing Doppler Institute of mathematical physics.