Those who have much leisure to think, will always be enlarging the stock of ideas; and every increase of knowledge, whether real or fancied, will produce new words, or combination of words.

When the mind is unchained from necessity, it will range after convenience; when it is left at large in the fields of speculation, it will shift opinions; as any custom is disused, the words that expressed it must perish with it; as any opinion grows popular, it will innovate speech in the same proportion as it alters practice.
As by the cultivation of various sciences a language is amplified, it will be more furnished with words deflected from their original sense; the geometrician will talk of a courtier's zenith or the eccentric virtue of a wild hero, and the physician, of sanguine expectations and phlegmatic delays.

Copiousness of speech will give opportunities to capricious choice, by which some words will be preferred, and others degraded; vicissitudes of fashion will enforce the use of new, or extend the signification of known terms.

The tropes of poetry will make hourly encroachments, and the metaphorical will become the current sense: pronunciation will be varied by levity or ignorance, and the pen must at length comply with the tongue; illiterate writers will, at one time or other, by public infatuation, rise into renown, who, not knowing the original import of words, will use them with colloquial licentiousness, confound distinction, and forget propriety.
As politeness increases, some expressions will be considered as too gross and vulgar for the delicate, others as too formal and ceremonious for the gay and airy; new phrases are therefore adopted, which must for the same reasons be in time dismissed.

Swift, in his petty treatise on the English language, allows that new words must sometimes be introduced, but proposes that none should be suffered to become obsolete.