Edward Sapir (18841939). Language: An Introduction to the Study of Speech. 1921.
genealogical kin of their formal prototypes. They are analogical replacements.
The history of the English language teems with such levelings or extensions. Elder and eldest were at one time the only possible comparative and superlative forms of old (compare German alt, älter, der älteste; the vowel following the old-, alt- was originally an i, which modified the quality of the stem vowel). The general analogy of the vast majority of English adjectives, however, has caused the replacement of the forms elder and eldest by the forms with unmodified vowel, older and oldest. Elder and eldest survive only as somewhat archaic terms for the older and oldest brother or sister. This illustrates the tendency for words that are psychologically disconnected from their etymological or formal group to preserve traces of phonetic laws that have otherwise left no recognizable trace or to preserve a vestige of a morphological process that has long lost its vitality. A careful study of these survivals or atrophied forms is not without value for the reconstruction of the earlier history of a language or for suggestive hints as to its remoter affiliations.
Analogy may not only refashion forms within the confines of a related cluster of forms (a paradigm) but may extend its influence far beyond. Of a number of functionally equivalent elements, for instance, only one may survive, the rest yielding to its constantly widening influence. This is what happened with the English -s plural. Originally confined to a particular class of masculines, though an important class, the -s plural was gradually generalized for all nouns but a mere handful that still illustrate plural types now all but extinct (foot: feet, goose: geese, tooth: teeth, mouse: mice, louse: lice; ox: oxen; child: children; sheep: sheep, deer: deer).