Aristoxenus describes the enharmonic genus (; ) as the "highest and most difficult for the senses" . Historically it has been the most mysterious and controversial of the three genera. Its characteristic interval is a ditone (or major third in modern terminology), leaving the "pyknon" to be divided by two intervals smaller than a semitone called dieses (approximately quarter tones, though they could be calculated in a variety of ways). Because it is not easily represented by Pythagorean tuning or meantone temperament, there was much fascination with it in the Renaissance. It has nothing to do with modern uses of the term "enharmonic".