actually that day is today, with the caveat that i am not a linguist. i'm just an early modernist (specialized in english drama). and this is not an exhaustive course in early modern english! it is a bare bones intro to the basics. if you want to know more, read early modern works or do some googling.
what kind of english is that? let's look at some famous examples of each.
Hwæt. We Gardena in geardagum, / þeodcyninga, þrym gefrunon, / hu ða æþelingas ellen fremedon. <- this is old english. note that it is unintelligible to a modern english speaker. (excerpt from beowulf)
Whan zephirus eek with his sweete breeth / Inspired hath in every holt and heeth / Tendre croppes, and the yonge sonne / Hath in the ram his halve cours yronne … <- this is middle english. it is more intelligible, but it’s still very different from what we speak now. (excerpt from the canterbury tales)
Is this a dagger which I see before me, / The handle toward my hand? Come, let me clutch thee. / I have thee not, and yet I see thee still. /
Art thou not, fatal vision, sensible / To feeling as to sight? <- this is early modern english. this is so intelligible that we trust teenagers to read it in school. (excerpt from macbeth)
the english you are using to give a post a medieval or renaissance/shakespearean vibe is early modern english, not old english. (it's fine that you're using early modern english for a medieval vibe; no one expects you to learn middle english for a silly post about knights.)
'thou' is the informal second-person singular pronoun.
thou is the nominative form. you can use it for the subject of a sentence -> thou knowest me.
thee is the oblique form. you can use it for the object of a sentence -> i know thee.
thy and thine are the genitive forms. you can use them as possessive adjectives for nouns starting with consonants and vowels respectively. -> thy leg is broken. thine arm is broken too.
thine is also the possessive form. think about it like the word 'mine'*. -> my heart was once thine.
*'mine' is also used like thine as a possessive adjective in early modern english; you would say 'mine art' instead of 'my art'
originally, 'ye' was the formal or plural nominitive second-person pronoun, and 'you' was the oblique form. so, it would be 'ye know me' and 'i know you'. 'ye' fell out of use and was replaced by 'you'. at that point it was already used as singular. but it was still much more formal than 'thou'.
the 'ye' you see in 'ye olde shoppe' stuff is not this pronoun. it is the way that printers who no longer had a thorn (þ) wrote the word 'the' (previously 'þe'). the 'y' in certain typefaces looked like a thorn, so we got 'ye' for 'the'.
how do you conjugate a verb?
you can't just slap a -th or -st onto the end of any verb. those are for specific conjugations. phrases like "i hath noticed" or "he thinkest that" are not grammatically sound. it's like saying "i has noticed" or "he think that".
the -st or -est ending is for (most) present and past tense verbs conjugated with 'thou'
some examples: thou canst, thou couldst, thou sayest, thou goest, thou wentest, thou hast, thou hadst, thou dost (or doest).
'thou' also has a few irregulars. some examples: thou wilt, thou art and thou wast (for 'to be'), thou shalt.
the -th or -eth ending is for (most) present and past tense conjugated with 'he', 'she', or 'it'
some examples: he hath, she sayeth, it doth, he goeth, she thinketh, it moveth
there are, of course, irregulars. the most important one is 'to be', which conjugates the same for this set as it does in modern english.
note: not every verb conjugates this way. for example, past tense verbs might use auxiliary verbs. so, not 'she cookedeth', but 'she did cook'.
by and large, the 'i', 'we', 'you' (or 'ye'), and 'they' conjugations were the same as they are today.
there were also some verbs that were used differently than we use them today, though (some of these fell out of use over the early modern period):
to be -> sometimes this verb is used instead of 'to have' as the auxiliary verb. 'i am arrived' means 'i have arrived', and 'she is come to see thee' means 'she has come to see you'.
to do -> sometimes this is used for the present progressive (i think that's the right name for it). 'he does speak' means 'he is speaking', and 'i do write' means 'i am writing'.
would -> this can be used to express a desire. 'i would i were a bird' means 'i wish i were a bird'
must -> this can be used without 'go' to mean 'must go'. 'i must to england' means 'i must go to england'
will -> this can be used without 'have' to mean 'will have'. 'you'll none of that' means 'you will have none of that'
there are a million other things i'm not covering, like different sentence structures for questions ('thinkest thou...?' as a valid alternative to 'dost thou think...?'), and different contractions ('she'll not' rather than 'she won't') but this post is long as fuck and i have things to do! enjoy! linguists, feel free to correct me on what name of tenses or declensions or whatever i have mixed up.
(psa: the point of this is not to be a kill-joy about other people's posts that have these errors. it's just a little knowledge sharing.)
