The mora is defined as something of which a long syllable ((C)VV or (C)VC) consists of two and a short syllable ((C)V) consists of one (McCawley 1968). According to some linguists, languages are classified into two groups: those that are best analysed in terms of morae and those that should be analysed in terms of syllables. Japanese is frequently cited as an example of a language that belongs to the former group. However, if the ultimate goal of the field of phonology is to seek for a group of principles that make up Universal Phonology, a unit such as the mora, which is indispensable in some languages but completely irrelevant in other languages, is an unwelcome innovation.