Third, the writing in the Book of Deer is of a thoroughly practical kind, relating to business transactions, and the Gaelic of the district must have been used. The very purpose of the memoranda was to substantiate claims against future mormaers and toisechs who might be disposed to dispute their legality. Fourth, it is believed that even in the Western Highlands, not to speak of Buchan, the difference between Irish and Scottish Gaelic was then wider than the literature would lead us to infer. For this reason, that the Gaelic MSS. of the period were produced by men who derived their culture from Ireland and naturally followed the Irish standard in their written compositions. The contents of the Book of Deer fully justify that conclusion. The Gaelic text is of the same age with that in the Leabhar Na h’Uidhre and Book of Hymns. Yet a comparison with these typical Irish monuments shows that the monks of Deer had developed peculiarities in writing Gaelic which differed considerably from the standard of the Irish scholars. Windisch, commenting upon this circumstance, says, “The manner of expression, words, and forms are as in the Irish, but the manner of writing shows already a stronger phonetic decay; whether it be that the Scotch Gaelic has lived faster, or that only the manner of writing has remained less ancient, and has fitted itself more exactly to the pronunciation of the time.” It is in this respect more like the Middle than the Ancient Irish. Those who are interested in the study of archaic words and grammatical forms will find the Book of Deer not a bad quarry; in fact our very oldest bed-rock for Scottish idioms. There are few declensional specimens, it is true, but these suffice to show, as Dr. Whitley Stokes observed, that the Highlanders declined their nouns in the eleventh century as fully as the Irish, which is very far from being the case to-day. Some of the peculiarities of the newly-fledged Scottish Gaelic may here be noticed. For example, that distinction of vowels so noticeable in the Authorised Version of the Scriptures, where we have the Irish _o_ in _focal_ instead of the Scottish _a_ as in _facal_, may be observed in the colophon of the Book of Deer, where we have _truagain_, “the poor wretch,” and not _trogan_ as in the Irish Priscian of St. Gall. Another feature is the confusion of vowels if ending words, as _i_ for _e_, the sinking of _c_ and _t_ to _g_ and _d_, and the assimilation of _ld_ and _ln_ to _ll_. The spelling has further local characteristics, perhaps due to Pictish influence, as, for example, _cc_ for _ch_; thus _imacc_ is for _imach_, modern _a mach_, “out of,” “henceforth;” _buadacc_ is for _buad(h)ach_, “victorious.”