Let us just stop on the way through linguistic history to take a quick glance at Middle English.
It seems astonishing now, but English just before the Black Death in the mid-14th century was a colloquial language of low status. The administrative and high language of England was Norman French (and the ecclesiastical language was Medieval Latin, based on Classical). Furthermore, English was spoken only in England and parts of Wales; the language descending from Anglo-Saxon in use in Scotland was recognised as a separate language, Scots.
The Black Death changed that somewhat, as it was indiscriminate, killing the French-speaking aristocracy in big numbers. As survivors rose up the social scale consequently, so did English; the King’s Speech was presented to Parliament in English for the first time in 1362. Soon, English also had Chaucer, a major literary figure. This, all combined with ongoing wars with France, saw English become the language of late medieval English nationalism. The rest of the rise from there to global status is history.
So what was the language of Chaucer like?
Phonology
There was no standard English at the time, but of course the bizarre linguistic truth is that modern Standard English spelling reflects it well, being based on the pronunciation of Middle English, not Modern English. This means a word like name ‘name’ was pronounced exactly as it looks (and as it still is in modern German); <e> was never silent. Words such as night were just losing the middle consonant sound (close to IPA /x/, cf. modern German Nacht) at the time of Chaucer. In words such as write, knife or gnat, the initial /w/, /k/ and /g/ were sounded; as was the /l/ in talk.
Anglo-Saxon regarded /f/ and /v/ as the same letter (the distinction was only brought in by the influence of Norman French), and these were still variously pronounced around the country and thus used in writing almost interchangeably in some areas. Scribes also used <v> and <u> interchangeably, treating them as absolutely the same letter.
Early Middle English also retained the letter “yogh” <ȝ>, which is usually (but not always) now /g/; it was pronounced somewhere between /g/ and /y/ before /e/ and /i/ (and similar vowels), but more like a hard /x/ (as in Scottish ‘loch‘) otherwise. It also retained “thorn” <þ>, now a <th>.
Standardisation
In the Middle English period, variations in spelling and usage were widespread, depending on geographical origin, exact time, and even on simply fitting on to the page or the line. People even wrote their own name variously! This mattered less, as proportionately fewer people were literate.
A “chancery standard”, forms to be used by the Civil Service in effect, did develop from the fifteenth century, but widespread standardisation only occurred well after the invention of the printing press into what is regarded as the (Early) Modern English period.
Vocabulary
Vocabulary was similarly mixed between Latinate (French and Latin) and Germanic origin as now, although there was a greater awareness of the distinction (the oldest known song in the English language, Sumer is icumen in ‘Summer has arrived’ dates from early Middle English, but its vocabulary is entirely Germanic).
Key numbers:
1 one, 2 tuo/twei, 3 thri, 4, fower, 5 five, 6 six, 7 sevene, 8 eight, 9 nine, 10 ten;
11 eleven, 12 twelve, 16 sixteen, 17 seventeen; 20 twenty, 24 fower-and-twenty;
100 hundred; 1000 thowsand;
456789 fower hundred six-and-fifty thowsand sevene hundred nine-and-eighty
NB: one was pronounced to rhyme with alone.
Ordinal numbers generally added -the, but from thri this was thridde.
Grammar
Nouns had largely lost the Anglo-Saxon “case” system, although the possessive remained, written -(e)s (no apostrophe). More irregular plurals remained in regular use (e.g. namen ‘names’).
Verbs “agreed” with their subject and had a wider range of endings with which to do so. There were more “strong” verbs (marking past forms by vowel change rather than an ending) than in Modern English; thus irregular help-halp-(i)holpen stood alongside sing-sang-(i)sungen. The i- or y- prefix (cf. German ge-) on participles was generally lost during this period.
Present of liken ‘to like’ (1st, 2nd, 3rd person):
Singular I like, thou likest, he/sche/hit liketh;
plural we liken, you liken, they liken.
Past participle liked; present participle likand; gerund liking.
Imperative like (singular); liketh (plural).
Past of liken ‘to like’ (1st, 2nd, 3rd person):
Singular I likede, thou likedst, he/sche/hit likede;
plural we likeden, you likeden, they likeden.
Past of singen ‘to sing’ (1st, 2nd, 3rd person):
Singular I sang, thou songe, he/sche/hit sang;
plural we songen, you songen, they songen.
Adjectives only “agreed” with nouns by adding -e after the definite article, a possessive or in the plural (but not otherwise): his longe name ‘his long name’, longe namen ‘long names’; a long name ‘a long name’. Adverbs were beginning to be distinguished (usually by the ending -liche, often reduced to -lie).
Pronouns maintained a distinction between the singular þu (later thou; object þe/thee) and plural ye (object you). Singular possessive forms came to be distinguished between mine/thine (the original forms, used latterly only before vowels) and my/thy (used before consonants) – cf. usage even in Modern English of the indirect article an/a.
Key personal pronouns (1st, 2nd, 3rd person):
Direct: I, þu/thou, he-sche-hit; we, ye, heo/they
Oblique: me, þe/thee, him-hir-hit; us, you, hem/them
Possessive: mine (my), þin/thine (thy), his-hir-his; oure, your, hire
Prepositions were similar to today, but there were also combined forms with locational pronouns in much wider use that in Modern English: hence ‘from here’; whither ‘where to’. One noteworthy preposition since lost was umbe ‘around’ (cf. modern German um).
Word order was predominantly SVO, and VSO in questions (Likest thou me? ‘Do you like me?’), although there were notable exceptions (the main part of the verb phrase often went to the end in subordinate clauses: whan he hath hire name sungen ‘when he has sung their name’). Negation was predominantly by addition of the particle nat (or similar) after the verb: he singeth nat ‘he does not sing’. This could be supported by a pre-verbal particle ne (effectively meaning doubled negation reinforced the negative): he ne singeth nouȝt ‘he sings nothing’.
Character
Middle English was more quintessentially Germanic in character than the modern language, but much less so than Anglo-Saxon.
Dialects varied but, unlike modern “BBC English”, Middle English was almost certainly spoken with a rising intonation; and it would have been more vocalic than the modern language (notably because /e/ was always pronounced).
What next?
Let us get to the modern day now… but with a twist…
Fader oure that art in heuene, halewed be þi name: come þi kyngdom: fulfild be þi wil in heuene as in erþe: oure ech day bred ȝef us to day, and forȝeue us oure dettes as we forȝeueþ to oure detoures: and ne led us nouȝ in temptacion, bote deliuere us of euel.