6. The A.S. ǣ, if answering to Gothic ai, produced M.E. open ē. But if answering to Goth. ē, the M.E. ē was close in the Midland dialect, but was allowed to rime with open ē in Southern; giving Chaucer a choice of forms.
7. The A.S. ēo and ē (if arising from mutation of ō) produced M.E. close ē.
8. In words such as A.S. gesȳne, Mercian gesēne, visible, the M.E. y-sēne had an ē which rimed with open ē in Kentish, and a close ē in Midland, giving Chaucer a choice of forms.
[§ 35]. It will be now easily understood, that Chaucer's general rule, of avoiding the riming of close ē with open ē, admits of a considerable number of exceptions, in which the ē is really of a doubtful or unstable character.
It is clear that, in considering Chaucer's forms, we must set aside, as UNSTABLE, all words in which long e corresponds either to a Germanic ǣ (Gothic ē, German ā), or otherwise to A.S. unstable ȳ (Mercian ē). I proceed to enumerate the chief of these, as occurring, first of all, in Troilus.
Words ending in -eche. The verb ēche, to eke, answers to A.S. ȳcan. Leche, a leech, is allied to Goth. lēkeis, a physician. Speche, speech, is from the stem seen in sprǣc-on, they spoke, with the same vowel, originally, as in Goth. brēkun, they broke. All these words have unstable e.
-ede. Dede, deed; A.S. dǣd, Goth. gadēds. Drede, to dread, A.S. on-drǣdan, O.H.G. trātan. From V. 1654-7, it is difficult to draw any clear inference; brede should have open ē (cf. A.S. brād, Goth. braids); hede, heed, goes with A.S. hȳdan, and its vowel is unstable; and Diomede, though the e should be close, is at proper name, and needs no exact treatment.
-eke. Besides the correct form èèk (A.S. ēac), Chaucer has a form eke, with unoriginal final e; he probably connected it with the verb eche, to eke, in which the e is unstable, as it arose from mutation.
Cheke answers to A.S. cēace, Anglian cēce, mod. E. cheek; but here the ēa is not the usual A.S. ēa, being merely due to the initial c, and the West-Germanic type is *kākā (New E. Dict.), answering to Germanic *kǣkā; whence the A.S. original form *cǣce; so that the e is unstable, by the rule above given.