Reine stimmung or naturliche stimmung means "pure natural tuning"; English is "new" or "pure", which means "correct" or "just intonation". The emergence of pure law theory must thank Pythagoras, a great mathematician in ancient Greece. He first explained that according to the length of strings, all intervals used at that time were calculated with one to two as a complete octave and two to three as a complete fifth degree. That is, the melody scale that we hum casually today.