Mencken on Don’t Not Use Double Negatives

In The American Language (1921), H.L. Menken wrote:

Like most other examples of “bad grammar” encountered in American the compound negative is of great antiquity and was once quite respectable. The student of Anglo-Saxon encounters it constantly.
…
Chaucer, at the beginning of the period of transition to Modern English, used the double negative with the utmost freedom. In “The Knight’s Tale” is this:

“He nevere yet no vileynye ne saydeIn al his lyf unto no maner wight.”

By the time of Shakespeare this license was already much restricted, but a good many double negatives are nevertheless to be found in his plays, and he was particularly shaky in the use of nor. In “Richard III” one finds “I never was nor never will be”; in “Measure for Measure,” “harp not on that nor do not banish treason,” and in “Romeo and Juliet,” “thou expectedst not, nor I looked not for.” This misuse of nor is still very frequent. In other directions, too, the older forms show a tendency to survive all the assaults of grammarians.

You can, of course, find more on the Internet about double (and triple and poly-negatives).