 During the second century AD, Claudius Ptolemy described a 5-limit diatonic scale in his influential text on music theory "Harmonics", which he called "intense diatonic".Given ratios of string lengths 120, 112 , 100, 90, 80, 75, 66 , and 60, Ptolemy quantified the tuning of what would later be called the Phrygian scale (equivalent to the major scale beginning and ending on the third note) – 16