Alexander MacBain,
An Etymological Dictionary of the Gaelic Language
(1911)
“ The term Gaelic means Modern Gaelic. Scottish Gaelic is written on the orthographic lines of Modern Irish, which in its turn represents the orthography of Old Irish. The greatest departure from ancient methods consists in the insistence now upon the rule of "Broad to broad and small to small." That is to say, a consonant must be flanked by vowels of the same quality, the "broad" being a, o, u, and the "small" e and i. Gaelic itself has fallen much away from the inflexional fulness of Old Irish. ”
