B.C. to St. Ætheria in the latter part of the fourth century or later. It
includes books by trained writers, like Horace and Petronius, who
consciously adopt the Latin of every-day life, and productions by
uneducated people, like St. Ætheria and the writers of epitaphs, who have
unwittingly used it.

St. Jerome says somewhere of spoken Latin that "it changes constantly as
you pass from one district to another, and from one period to another" (et
ipsa Latinitas et regionibus cotidie mutatur et tempore). If he had added
that it varies with circumstances also, he would have included the three
factors which have most to do in influencing the development of any
spoken language. We are made aware of the changes which time has brought
about in colloquial English when we compare the conversations in Fielding
with those in a present-day novel. When a spoken language is judged by the
standard of the corresponding literary medium, in some of its aspects it
proves to be conservative, in others progressive. It shows its
conservative tendency by retaining many words and phrases which have
passed out of literary use. The English of the Biglow Papers, when
compared with the literary speech of the time, abundantly illustrates this
fact. This conservative tendency is especially noticeable in districts
remote from literary centres, and those of us who are familiar with the
vernacular in Vermont or Maine will recall in it many quaint words and
expressions which literature abandoned long ago. In Virginia locutions may
be heard which have scarcely been current in literature since
Shakespeare's time. Now, literary and colloquial Latin were probably drawn
farther apart than the two corresponding forms of speech in English,
because Latin writers tried to make the literary tongue as much like Greek
in its form as possible, so that literary Latin would naturally have
diverged more rapidly and more widely from conversational Latin than
formal English has drawn away from colloquial English.