  Commented translation of the paper "Universelle Bedeutung des
Wirkungsquantums", published by Jun Ishiwara in German in the Proceedings of
Tokyo Mathematico-Physical Society 8 106-116 (1915). In his work, Ishiwara,
tenured at Sendai University, Japan, proposed - simultaneously with Arnold
Sommerfeld, William Wilson and Niels Bohr in Europe - the pase-space-integral
quantization, a rule that would be incorporated into the old-quantum-mechanics
formalism.
