At every stage the structure of language is nothing but the unstable balance between the needs of communication, which require more numerous and more specific units, each of them of comparatively rare occurrence, and man’s inertia, which favours less numerous, less specific, and more frequently occurring units. It is the interplay of these two main factors that constitutes the essential of linguistic economy.
- Martinet (1962), a pag.139

Inertia combined with redundancy delays the spread of all the parts of the language structure of the repercussions of some initial change.
- Martinet (1962), a pag.138