Alexander MacBain,
An Etymological Dictionary of the Gaelic Language
(1911)
“ The Brittonic languages—Welsh, Cornish, and Breton—appear first in glosses as early as the eighth century. These glosses are marginal or super-linear translations into Celtic of words or phrases in the Latin texts contained in the MSS. so "glossed." The period of the glosses is known as the "Old" stage of the languages—Old Breton, Old Cornish, Old Welsh. Real literary works do not occur till the "Middle" period of these tongues, commencing with the twelfth century and ending with the sixteenth. ”
