OE = Old English,
ME = Middle English (c. 1150-1450),
MnE = Modern English.
Grammar
The main grammatical difference between OE and ME was the loss of most
inflections.
Old English was a heavily
inflected language like
German. The reduction and loss of these inflections began before 1066, notably in the
Danelaw where it was in contact with speakers of the closely related
Old Norse, but it accelerated after the
Conquest.
The OE dative plural -um changed to -en, becoming identical with an existing ending and also with endings -an and -on. Endings -e, -a, and -u also merged. These unstressed vowels lost their distinctive sounds and became the schwa or neutral vowel, as in MnE bitten, button. Eventually all these endings, now written -e, became silent, and the final -e served only to mark the length difference between e.g. rat and rate. The silent -e lingered in spelling for many centuries more.
Where OE had a multiplicity of plural formations, ME generalized the -s, -es ending, keeping a lesser number with -en (of which several remain, like oxen).
In OE, past participles had the prefix ge- as in German (er ist gekommen 'he has come'). In ME this become i- (also written y-), and eventually disappeared. Its legacy is the odd archaism like yclept, and the song Sumer is icumen in, which means 'Summer has come in' (cf. German), not 'is coming in'.
OE had a distinct present participle in -and (German -end) as in 'a laughing hyena', and gerund in -ing (German -ung), as in 'laughing is infectious'. In ME the gerund was generalized and the participle dropped out.
Literature
The principal monument of ME literature is of course
The Canterbury Tales. Because
Chaucer was a
Londoner, his dialect is the ancestor of the kind of English most of us now speak, so is rather easier to understand than the contemporary poem
Sir Gawain and the Green Knight, from the North-West Midlands. This is a pity, since
Gawain is a beautiful poem, well worth struggling through. Other important literature of the period includes
Piers Plowman,
Pearl,
Patience,
Ancrene Riwle (rules for
anchoresses),
Ayenbite of Inwit (remorse of conscience),
Sir Orfeo, and the historical-cum-legendary
Brut of
Layamon, which includes a version of the
King Arthur story.
There is a long didactic poem Ormulum by a monk called Orm. It is stupefyingly boring as literature, but fascinating as language because Orm tried to institute a spelling reform in which a short vowel was indicated by doubling the following consonant. This provides a very valuable guide to the pronunciation of ME. It's sad that it's virtually never credited as the Orrmulum of Orrm, as he wanted.
Dialects
OE had four principal dialects,
Northumbrian,
Mercian,
West Saxon, and
Kentish. The standard literary language in the later period was West Saxon, that of the court of King
Alfred at
Winchester in
Wessex. Because of the Danish occupation of the east, Mercian was dividing into two,
West Midland and
East Midland. From
1066 the centre of culture was
London, midway between the Kentish and East Midland areas. As the new universities of
Oxford and
Cambridge were also in the East Midlands, it is this
dialect that became the basis of standard modern English.
The northern dialect remained uniform until about 1300, then over the next hundred years rapidly diverged into three, those of Yorkshire, Northumberland, and lowland Scotland. Yorkshire was influenced by the south, and took on an intermediate character. As Scotland was an independent kingdom, the Scots or Lallans dialect was increasingly perceived as a separate language. This identity diminished after the union with England in 1603. Characteristic features include plural -is, a strong fricative spelt quh for southern wh, and the fact that long a didn't change to o as it did in the south (hame, camb).
Both the southern dialects used voiced versions of f, s initially: vriend, zummer. Kentish later lost this but it may still be heard provincially in the South-West. The modern word vixen comes from a southern feminine of fox.
Vocabulary
From about 1250 the trickle of
borrowings from
French turned into a flood, turning English into the hybrid it is today.
It must be borne in mind that French has also changed a great deal since then, and the pronunciation of borrowed words would have been quite different from modern French. The ending -ation would have been more like -AH-see-ohn.
Pronunciation
ME spelling is confused, to say the least. The change of sounds from OE, in the different dialects, and with overlay of French habits, produced a complex system that was stabilized but not standardized when
printing came in at the end of the ME period. But because OE spelling was more accurately phonetic, we can untangle many of the details of the sound changes of ME.
The guttural written with yogh, later gh, often disappeared in the southern dialects, leaving a long vowel, as in light, though. In other circumstances it became y as in day, w as in law, or f as in rough.
The clusters ld, nd, mb caused short vowels to lengthen: wild, blind, climb.
Middle English comes to an end as the Great Vowel Shift wreaks major changes on its pronunciation. Before this you could pronounce it roughly like any other European language. After it comes the Early Modern English of the Elizabethan/Jacobean playwrights and the Authorized Version.