[1.] Before a nasal + consonant, as OE. wind, OHG. MHG. wint, Lat. ventus, wind; OHG. fimf, finf, Gr. πέντε, five. This explains why verbs like MHG. binden, to bind, rinnen, to run, singen, to sing, belong to the same ablaut-series as hëlfen, to help, wërden, to become.
[2.] Before other consonants when followed by an ī̆ or j in the next syllable, and further in OHG. when followed by an u in the next syllable, as OHG. MHG. ist, Gr. ἐστί, is; OHG. fihu, Lat. pecu, cattle; ërde (OHG. ërda), earth, but irdīn, earthen; ligen (OHG. liggen from *ligjan), to lie down, sitzen (OHG. sitzen from *sitjan), to sit, but p.p. gelëgen (OHG. gilëgan), gesëȥȥen (OHG. gisëȥȥan). This explains why strong verbs belonging to the fourth (§§ [12], [82]) and fifth (§§ [12], [83]) ablaut-series have i throughout the present singular, and similarly in verbs belonging to the third (§§ [12], [81]) series with ë in the infinitive, as
| OHG. nëman, to take, | three persons sing. | nimu, nimis(t), nimit. |
| MHG. nëmen,„ | „„„ | nime, nimes(t), nimet. |
| OHG. gëban, to give, | „„„ | gibu, gibis(t), gibit. |
| MHG. gëben,„ | „„„ | gibe, gibes(t), gibet. |
| OHG. hëlfan, to help, | „„„ | hilfu, hilfis(t), hilfit. |
| MHG. hëlfen,„ | „„„ | hilfe, hilfes(t), hilfet. |
[§ 15.] u, followed originally by an ā̆, ō̆, or ē in the next syllable, became o when not protected by a nasal + consonant or an intervening ī̆ or j; hence the interchange between u and o in the preterite plural and past participle of verbs belonging to the second ablaut-series (§§ [12], [78]), as bugen (OHG. bugum), we bent, p.p. gebogen (OHG. gibogan); in the p.p. of verbs belonging to the third ablaut-series (§§ [12], [81]), as gebunden (OHG. gibuntan), but geholfen (OHG. giholfan); in weak verbs as fürhten (OHG. furhten from *furhtjan), to fear, beside pret. vorhte (OHG. forhta); hügen (OHG. huggen from *hugjan) beside hogen (OHG. hogēn), to think; in preterite presents like durfen (OHG. durfum), we dare, beside pret. dorfte (OHG. dorfta); in many nouns and adjectives, as wolle (OHG. wolla), wool, beside wüllīn, wullīn, woollen; wolf (stem *wulfo-), wolf, beside wülpinne, she-wolf; vol, full, beside vülle (OHG. fullī), fulness; golt, gold, beside guldīn, golden.
[§ 16.] From primitive Germanic eu were developed two different diphthongs in OHG., viz. eu became eo (cp. [§ 15]), later io, when originally followed by an ā̆, ō̆, or ē in the next syllable, and this io was regularly developed to ie in MHG.; whereas eu became iu in OHG. when originally followed by an ī̆, j or u in the next syllable, and this iu became ǖ (written iu) in MHG., even after the ī̆, j or u had been weakened to e. This law explains the difference between the diphthong ie in the infinitive and the simple vowel iu (= ǖ) in the three persons singular of the present indicative of verbs belonging to the second ablaut-series (§§ [12], [78]), as
| OHG. biogan, to bend, | pres. sing. | biugu, biugis(t), biugit; |
| MHG. biegen,„ | „„ | biuge, biuges(t), biuget. |
Cp. further tief (OHG. tiof), deep, beside OHG. tiufī, depth; lieht (OHG. lioht), a light, beside liuhten (OHG. liuhten from *liuhtjan), to light.
[Note.]— The iu in the above and similar examples must not be confounded with the iu in the OHG. and MHG. combination iuw which arose from prim. Germanic eww (= euw), and ewj, as triuwe (OHG. triuwi, Goth. triggws), true; triuwen, trūwen, to trust, pret. triuete, triute, trūte; riuwe (OHG. riuwa), regret, bliuwen (OHG. bliuwan, Goth. bliggwan), to strike, and similarly, briuwen, to brew, kiuwen, to chew, riuwen, to regret; niuwe (OHG. niuwi, Goth. niujis, prim. Germanic stem-form *newja-), new. This iu before w never interchanged with MHG. ie from prim. Germanic eu, and explains why the strong verbs bliuwen, &c. have iu in all forms of the present.
[§ 17.] Accented primitive Germanic ai (= Goth. ái) became ē in OHG. before r, w, Germanic h (cp. [§ 23, 1]), and finally; in MHG. it appears also as ē before the same consonants and finally, as mēre, mēr (OHG. mēro, Goth. máiza), more, lēren (OHG. lēren, Goth. láisjan), to teach; sēle (OHG. sēla, older sēula, Goth. sáiwala), soul; snē (OHG. snēo, Goth. snáiws), snow, gen. OHG. and MHG. snēwes; spīwen, to spit, pret. spē (OHG. spēo, Goth. spáiw); dīhen, to thrive, pret. dēch (OHG. dēh, Goth. dáih); wē (OHG. wē, Goth. wái), woe!; in all other cases ai became ei in both OHG. and MHG., as stein (Goth. stáins), stone, heiȥen (OHG. heiȥan, Goth. háitan), to call; snīden, to cut, pret. sneit (OHG. sneid, Goth. snáiþ). This accounts for the difference between the ei and ē in the preterite singular of strong verbs belonging to the first ablaut-series (§§ [12], [76]).
[§ 18.] Primitive Germanic au became ō in OHG. before the consonants d, t, ȥ, s, n, r, l, and Germanic h (cp. [23, 1]). Before other consonants and finally au became ou in the ninth century. Hence the difference between ō and ou in the preterite singular of strong verbs belonging to the second ablaut-series (§§ [12], [78]), as:—