"[T]he results... hitherto quoted... taken in their totality, form an overwhelming proof of the existence of the quantum of action, the quantum hypothesis received its strongest support from the theory of the structure of atoms (Quantum Theory of Spectra) proposed and developed by Niels Bohr... the long-sought key to the gates of the wonderland of spectroscopy which since the discovery of spectrum analysis... stubbornly refused to yield. And... once clear, a stream of new knowledge poured in a sudden flood, not only over this... field but into the adjacent territories of physics and chemistry."