Most writing systems are interpreted as referring in some way to the phonetic composition of speech forms. In the process the natural continuous flow of sound is artificially broken up into discrete units of various size. The syllable is an intuitively salient unit exploited to this end by several ancient and modern writing system such as Assyrian cuneiform, Cypriot and Japanese kana (...). Syllables are typically composed of consonants and vowels, which, in the Western tradition, as a reflection of the Greek alphabet are both uniformly considered sound segments, while in Semitic writing consonants and vowels are conceptualized and symbolized differently. The use of 'matres lectionis' in archaic Semitic documents is clear evidence that the Semitic scribes had a notion of a vowel as a unit of language. For reasons having to do with the conservative nature of writing systems in general and with the semantic significance of consonants in Semitic languages, they chose not to, or were not able to, treat both classes of sounds in the same manner.
All writing systems are based on, and hence more or less explicitly incorporate a linguistic analysis. In the case of Indian writing systems this is especially obvious.