 Regarding Bohr’s correspondence principle, the historian of physics Max Jammer writes, “[T]here was rarely in the history of physics a comprehensive theory which owed so much to one principle as quantum mechanics owed to Bohr’s correspondence principle” (Jammer 1966, p. 118). The correspondence principle not only played a pivotal role in the discovery of quantum mechanics but was also the cornerstone of Bohr’s philosophical interpretation of quantum mechanics, being closely tied to his better known thesis of complementarity and to the Copenhagen interpretation.