Originally, “thou” was used to address anyone, regardless of status or relationship; “ye”/”you” was only used to address more than one person.

In Middle English, there were the following pronouns (subject form first, object form second):

“I”/”me”, first person singular, corresponding to German “ich”
“thou”/”thee”, second person singular, corresponding to German “du”
“he”/”him”, third person singular masculine, corresponding to German “er”
“she”/”her”, third person singular feminine, corresponding to German “sie”
“it”/”it”, third person singular neuter, corresponding to German “es”
“we”/”us”, first person plural, corresponding to German “wir”
“ye”/”you”, second person plural, corresponding to German “ihr”
“they”/”them”, third person plural, corresponding to German “sie”

After the model of French “tu” vs. “vous”, “ye”/”you” was increasingly used as a polite or distanced form in Middle English. “Thou”/”thee”, however, remained as a more “intimate” form.

To be more precise I think “thou” conveyed that one considered the other as being on the same societal level or a lower one, while “ye” was a kind of submissive gesture to those considered superior.

The same development happened in Middle High German as well, even though “Ihr” as a form of address for a single person is now considered archaic and present only in a few local dialects (I only knew about Swiss dialects where this is used, that about Franconia is news to me).

In Southern England, probably London, there seems to have started a fashion in the 16th or 17th centuries (in Shakespeare’s time) to address EVERYONE with the high-status, polite form. Possibly as a form of urban dwellers to distance themselves from the country yokels who’d only ever use “thou” among themselves and “ye”/”you” only for urbanites (I guess - just like in modern times, rural people in Southern Germany, Austria or Switzerland would address every tourist from Northern Germany, who usually were urbanites, using terms along the lines of English “lord” or “lady”).

So, Londoners - considering themselves refined and cosmopolitan - would use the fashionable “ye”/”you” (modelled after French) among themselves, implying that everyone was of high status, or just because it was considered polite to address your conversation partner in a respectful manner. This would turn “ye”/”you” more into a sign that you consider the other one your equal.

In turn, “thou” remained the intimate way to address God, or people treated as of lower status. As in Shakespeare, this could be used deliberately to insult people by denying them respect. The combination God vs. pejorative use appears curious only on the surface: Talking to God was considered as intimate as it gets, but using “thou” for a fellow man was insulting if it was used INAPPROPRIATELY.

Another change that happened is that “ye”, still in use in some places in Ireland, disappeared from most places and was replaced by the object form “you”, now also used as subject form.

The King James Bible in the early 17th century was deliberately written in a style that seemed archaic even at the time, and used “thou”.

In regional dialects of English, “thou” has still not disappeared completely everywhere. It disappeared first in Southeast England, but in other regions it may still be heard until the present day.

The Quakers used “thou” instead of “you” to address each other at a time because of their preferrence of “plain” speech, to convey equality among them. “You” as a “fancy” pronoun conflicted with the ideal of “plain” speech and was thus avoided by them.

Over time, the original use of “thou” was forgotten by speakers of Standard English and as people felt it to be a “special” and archaic pronoun, used to address God and a frequent occurrence in the King James Bible (and also Shakespeare). Therefore, people feel “thou” to be “fancy” now, when it was originally the other way round.

The historically correct way to translate “Du darfst ruhig du zu mir sagen” into English would be “Thou canst say thou to me”, keeping in mind the explanations given.

Man, I’ve known my friend for eight years and were still on Sie terms. Everyone else is du. Irony.

I remember my mom adressing her mother in law (=my grandma) that way.

It was not used to “keep distance” here (they were actually quite close)…it was more of a way to show respect to the elder…

I found it always kinda strange tho, it sounded a bit ancient/old-fashioned…

The (partially true) stereotype is that in those regions driving instructors are using that form. It is also often in small shops (Tante Emma Läden).

But I don’t think that this form is in danger more than the dialect itself is in danger. In dialect this form is so convenient to use: basically its a nearly inaudible “?r” that is appended to the previous word.

Henn?r des gsäa? (Did you see that?)
Do miaßdad?r lenggs! (Please turn left over there!)

If I think about it, this is nearly an American behaviour, cause it gives you the opportunity to be polite and also be very clear how you think about this matter.

Unfortunately, this third form is falling more and more into oblivion.

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