Edward Sapir (18841939). Language: An Introduction to the Study of Speech. 1921.
fedan. The new long e-vowel fell together with the older e- vowel already existent (e.g., her here, he he). Henceforward the two are merged and their later history is in common. Thus our present he has the same vowel as feet, teeth, and feed. In other words, the old sound pattern o, e, after an interim of o, ö, e, reappeared as o, e, except that now the e had greater weight than before.
6. Fot: fet, mus: müs (written mys) are the typical forms of Anglo-Saxon literature. At the very end of the Anglo-Saxon period, say about 1050 to 1100 A.D., the ü, whether long or short, became unrounded to i. Mys was then pronounced mis with long i (rhyming with present niece). The change is analogous to 5, but takes place several centuries later.
7. In Chaucers day (circa 13501400 A.D.) the forms were still fot: fet (written foot, feet) and mus: mis (written very variably, but mous, myse are typical). About 1500 all the long i-vowels, whether original (as in write, ride, wine) or unrounded from Anglo-Saxon ü (as in hide, bride, mice, defile), became diphthongized to ei (i.e., e of met + short i). Shakespeare pronounced mice as meis (almost the same as the present Cockney pronunciation of mace).
8. About the same time the long u- vowels were diphthongized to ou (i.e., o of present Scotch not + u of full). The Chaucerian mus: mis now appears as the Shakespearean mous: meis. This change may have manifested itself somewhat later than 7; all English dialects have diphthongized old Germanic long i.8 but the long undiphthongized u is still preserved in Lowland Scotch, in which house and mouse rhyme with our loose. 7 and 8 are analogous developments, as were 5 and 6; 8