In PIE, vowel alternations called ablaut were frequent and occurred in many types of word, not only in verbs.
The basic vowel was *e (e-grade), but, depending on what syllable of a word the stress fell on in PIE, this could change to *o (o-grade), or disappear altogether (zero grade).
Thus ablaut turned short e into the following sounds: As the Germanic languages developed from PIE, they dramatically altered the Indo-European verbal system.
To compensate for this, a new type of past tense was eventually created for these verbs by adding a -d- or -t- suffix to the stem.
The coherence of the strong verb system is still present in modern German, Dutch, Icelandic and Faroese.
Some verbs, which might be termed "semi-strong", have formed a weak preterite but retained the strong participle, or rarely vice versa.
– While the inflections are more or less regular, the vowel changes in the stem are not predictable without an understanding of the Indo-European ablaut system, and students have to learn five "principal parts" by heart.
These are: Germanic strong verbs are commonly divided into seven classes, based on the type of vowel alternation.
The reverse process in which anomalies are eliminated and subgroups reunited by the force of analogy is called "levelling", and it can be seen at various points in the history of the verb classes.
In the later Middle Ages, German, Dutch and English eliminated a great part of the old distinction between the vowels of the singular and plural preterite forms.
The following phonological changes that occurred between Proto-Indo-European and Proto-Germanic are relevant for the discussion of the ablaut system.
Its ending is also an -i of unclear origin, rather than the expected -t < PIE *-th₂e of North and East Germanic, which suggests that this state of affairs is an innovation.
Instead of (or in addition to) vowel alternations, this class displayed reduplication of the first consonants of the stem in the past tense.
The vowel alternation was retained in a few class 7d verbs, but eliminated otherwise by generalising the present tense stem throughout the paradigm.
Jasanoff posits the following series of events within the history of Northwest Germanic:[5] Stages 4 and 5 were not quite complete by the time of the earliest written records.
*e in class 7c was replaced by *ē (> ia) in Old High German and Old Dutch, but by *eu (> ēo) in Old English.
Being the oldest Germanic language with any significant literature, it is not surprising that Gothic preserves the strong verbs best.
Class 1 roots in modern English (excluding derived verbs such as abide and override) are bide, bite, chide, drive, hide, ride, rise, rive, shine, shit/shite, shrive, slide, smite, stride, strike, strive, thrive, write.
However, although most of these verbs have uniformity in their infinitive vowel, they no longer form a coherent class in further inflected forms – for example, bite (bit, bitten), ride (rode, ridden), shine (shone, shone), and strike (struck, struck/stricken, with struck and stricken used in different meanings) all show different patterns from one another – but bide, drive, ride, rise, smite, stride, strive, write do form a (more or less) coherent subclass.
It includes choose, cleave, fly, freeze and shoot (whose usual passive participle is shot rather than shotten).
Many of the verbs have two past forms, one of which may be dialectal or archaic (begin, drink, ring, shrink, sing, slink, spin, spring, stink, swing, swim and wring).
Class 4 verbs in English (not including derivatives such as beget) are bear, break, get, shear, speak, steal, swear, tear, tread, wake, weave; and without the -n and of irregular vowel progression: come.
The verb come is anomalous in all the West Germanic languages because it originally began with qu-, and the subsequent loss of the w sound coloured the vowel of the present stem.
Class 6 verbs in modern English: drag, draw, forsake, lade, shake, shape, shave, slay, stand, take.
Two preterites (drew and slew) are now spelled with "ew", which is similar in sound to the "oo" of the others that still use a strong form.
Lade, shape, shave, wax are now weak outside of their optionally strong past participle forms (laden, shapen, shaven, and waxen respectively).
For instance, compare strong and figurative bedorwe jeug ("spoiled youth") to weak and literal bederfde yoghurt ("spoiled yoghurt"), or strong and figurative gebroke hart ("broken heart") to weak and literal gebreekte vaas ("broken vase").
For instance, the strong participles are used in bevrore groente ("frozen vegetables") and aangenome kinders ("adopted children").
The following changes occurred from West Germanic to Old Saxon: From Old Saxon to Middle Low German: As in Middle Dutch Lengthening of vowels in open syllables: e > ē, o > ō, a > ā, ö > ȫ, ü > ǖ. i Is often lengthened to ē.
Class 3b on the other hand has shrunk in the modern language to only a few members, most of the remaining verbs now often appear with weak forms as well, making this subclass fairly unstable.