OBS. 1.—­Enallage is a Greek word, signifying commutation, change, or exchange.  “Enallage, in a general sense, is the change of words, or of their accidents, one for another.”—­Grant’s Latin Gram., p. 322.  The word Antimeria, which literally expresses change of parts, was often used by the old grammarians as synonymous with Enallage; though, sometimes, the former was taken only for the substitution of one part of speech for an other, and the latter, only, or more particularly, for a change of modification—­as of mood for mood, tense for tense, or number for number.  The putting of one case for an other, has also been thought worthy of a particular name, and been called Antiptosis.  But Enallage, the most comprehensive of these terms, having been often of old applied to all such changes, reducing them to one head, may well be now defined as above, and still applied, in this way, to all that we need recognize as figures.  The word Enallaxis, preferred by some, is of the same import.  “ENALLAXIS, so called by Longinus, or ENALLAGE, is an Exchange of Cases, Tenses, Persons, Numbers, or Genders.”—­Holmes’s Rhet., Book i, p. 57.

   “An ENALLAXIS changes, when it pleases,
    Tenses, or Persons, Genders, Numbers, Cases.”—­Ib., B. ii, p. 50.

OBS. 2.—­Our most common form of Enallage is that by which a single person is addressed in the plural number.  This is so fashionable in our civil intercourse, that some very polite grammarians improperly dispute its claims to be called a figure; and represent it as being more ordinary, and even more literal than the regular phraseology; which a few of them, as we have seen, would place among the archaisms.  The next in frequency, (if indeed it can be called a different form,) is the practice of putting we for I, or the plural for the singular in the first person.  This has never yet been claimed as literal and regular syntax, though the usages differ in nothing but commonness; both being honourably authorized, both still improper on some occasions, and, in both, the Enallage being alike obvious.  Other varieties of this figure, not uncommon in English, are the putting of adjectives for adverbs, of adverbs for nouns, of the present tense for the preterit, and of the preterit for the perfect participle.  But, in the use of such liberties, elegance and error sometimes approximate so nearly, there is scarcely an obvious line between them, and grammarians consequently disagree in making the distinction.