The work of analysis leads right up to the statements which enable anyone to synthesize or predict utterances in the language. These statements form a deductive system with axiomatically defined initial elements and with theorems concerning the relations among them. The final theorems would indicate the structure of the utterances of the language in terms of the preceding parts of the system. There may be various ways of presenting this system, which constitutes the description of the language structure. The system can be presented most baldly in an ordered set of statements defining the elements at each successive level or stating the sequences which occur at that level. Compactness, inspectability, and clarity of structure may be gained at various points by the use of symbols for class, variable member, and relation, or by the construction of geometric models (diagrams). Other types of presentation which have frequently been used have depended ultimately on moving-parts models such as machines or historical sciences. In using such models, the linguistic presentation would speak, for example, of base form (e.g. in morphophonemics, where the observed forms are obtained from the base form by applying a phonemic substitution), of derived forms (e.g. stems plus those affixes which are added first in the descriptive order might be called derived stems), or processes which yield one form out of another. In all these types of presentation, the elements are seen as having histories, so that the relation of an element to sequences which contain it becomes the history of the element as it is subjected to various processes and extensions.
- Harris (1951), a pag.373