(Writing Systems: An introduction to their linguistic analysis, Florian Coulmas)
All writing system incorporate linguistic analysis, and all writing systems are linear. (...) analyticity and linearity can be, and often are, manifest on different levels. Recognition of this fact helps to resolve a number of confusions about the proper classification of some writing systems. (...) To say that writing systems incorporate linguistic analysis does not mean that first there was a proper analysis of speech and then there was writing. It just means that dissection of the stream of speech into constituent parts is indispensable for writing to occur. Only a few writing systems are the result of deliberate design and can accordingly be said to represent linguistic features that were found suitable for recording the languages in question. More commonly, the interpretation of written signs and the analytic understanding of linguistic structure have advanced together, one contributing to the other. A linguistic fit thus evolved. This explains the great diversity of the world's writing systems, which tend to highlight different units, reflecting the linguistic environments in which they developed. But no matter how we answer the question of whether writing they developed, preceded or accompanied the recognition of different levels of linguistic structure, it is clear that, by virtue of the fact that every writing system maps onto a linguistic system, it embodies and visibly exhibits the dissection of units of language and thus linguistic analysis.
However, since this analysis has in many instances evolved after the fact, it is not necessarily very systematic. Moreover, the breakdown inherent in the writing system may not reflect the salient units of the language very directly or very adequately, because language changes tends to disrupt the linguistic fit. Chinese offers a good example. When the Chinese writing system came into existence, Chinese words were predominantly one-syllable-one-morpheme units. This lexical structure is still reflected in today's Chinese writing, which treats individual characters rather than words as relevant units, although two-syllable words not necessarily consisting of two morphemes are very common in contemporary Chinese. Indeed, many Chinese characters do not make any sense but as part of a compound word. The lesson to be learned is that not every linguistic feature reflected in writing is always functionally relevant. More generally, a distinction has to be made between the unit of analysis - that aspect of linguistic structure encoded by the basic unit of a writing system - and the unit of interpretation - the constituent most relevant for processing a text and assigning it a linguistic interpretation. It is very common that there is no or only partial congruence between these two units.
Alice Faber (1992: 121), in the passage quoted at the beginning of this chapter, alerts us to a particular consequence of the disparity between the units of analysis and the units of interpretation. Scripts are linear. Spatial succession corresponds in one way or another to temporal duration. This is true in a very general sense and does not mean that all graphic components are interpreted consecutively, one after the other. The direction of a script, from left to right, from right to left, or from top to bottom, mirrors the temporal flow of connected speech, but this does not imply that the basic functional units of writing always appear in the same linear order as the linguistic units they encode. The extent to which there is agreement between the linear order of units of speech and units of writing is agreement between the linear order of units of speech and units of writing is an index of the relative simplicity of the writing system.