The sub-title of this symposium is accurate and, in a curious way, promises more than it states: Classical Physicist, Modem Philosopher. Heinrich Hertz, as the con- summate experimentalist of 19th century technique and as brilliant clarifying critic of physical theory of his time, achieved one of the fulfilments but at the same time opened one of the transition points of classical physics. Thus, in his 'popular' lecture 'On the Relations Between Light...