Language prescriptivism has a long genealogy

Letters of Cicero, Letter 258 to Brutus, Loeb translation:

…practically every one, unless his life was passed outside Rome, or some crudeness of home environment had tainted his speech, in those days spoke well and correctly. But lapse of time has brought about some deterioration in this respect both at Rome and in Greece. For as to Athens, so to our city, there has been an influx of many impure speakers coming from different places. It has created a situation which calls for a purge of language and the invoking of theory as an objective control or touchstone, not subject to change like the easily distorted rule of common usage.