, {fuo[z]i}, _feet_,
= MHG. {gr[u:]ene}, {v[u:]e[z]e}.

ABLAUT (VOWEL GRADATION).

Sec. 12.

By ablaut is meant the gradation of vowels both in stem and suffix,
which was chiefly caused by the primitive Indo-Germanic system of
accentuation. See the Author's Historical German Grammar, Sec. 23.

The vowels vary within certain series of related vowels, called
ablaut-series. In MHG. there are six such series, which appear most
clearly in the stem-forms of strong verbs. Four stem-forms are to be
distinguished in a MHG. strong verb which has vowel gradation as the
characteristic mark of its different stems:--(1) the present stem, to
which belong all the forms of the present, (2) the stem of the first or
third person of the preterite singular, (3) the stem of the preterite
plural, to which belong the second person of the preterite singular and
the whole of the preterite subjunctive, (4) the stem of the past
participle.

By arranging the vowels according to these four stems we arrive at the
following system:--

i. ii. iii. iv.

I. [i] ei, [e] i i
II. ie ou, [o] u o
III. i, [e:] a u u, o
IV. [e:] a [a] o
V. [e:] a [a] [e:]
VI. a uo uo a

NOTE.--1. On the difference between {ei} and {[e]}, see Sec. 17; {ou} and
{[o]}, Sec. 18; and in Series III {i} and {[e:]}, Sec. 14; {u} and {o},
Sec. 15.

2. Strong verbs belonging to Series II have {iu} in the indicative
pres. singular; and strong verbs belonging to Series III-V with {[e:]}
in the infinitive have {i} in the indicative pres. singular
(Secs. 14, 16).

EXAMPLES.

I. sn[i]den, _to cut_ sn[i]de sneit sniten gesniten;
l[i]hen, _to lend_ l[i]he l[e]ch lihen gelihen.
II. biegen, _to bend_ biuge bouc bugen gebogen;
sieden, _to seethe_ siude s[o]t suten gesoten.
III. binden, _to bind_ binde bant bunden gebunden;
h[e:]lfen, _to help_ hilfe half hulfen geholfen.
IV. n[e:]men, _to take_ nime nam n[a]men genomen.
V. g[e:]ben, _to give_ gibe gap g[a]ben geg[e:]ben.
VI. graben, _to dig_ grabe gruop gruoben gegraben.

For further examples see the various classes of strong verbs Secs. 76-86.
Class VII of str