Continental Celtic, which includes all Celtic idioms on the Continent with the exception of Breton, died out following the fall of the Western Roman Empire in the late 5th cent. A.D. The principal example of this group is the now extinct language Gaulish, for little remains of any other Continental Celtic tongues. Gaulish was once the language of Gaul proper (now modern France). Evidence of Gaulish is found both in words and in personal and proper names referred to by ancient Greek and Latin writers as well as in more than a hundred Gaulish inscriptions from France and N Italy (ranging in date from the 3d cent. B.C. to the 3d cent. A.D.). Coins and Greek and Latin inscriptions in Europe also preserve Celtic place-names and personal names. Yet the material as a whole is quite limited, furnishing only a number of proper names, a small vocabulary, and certain indications regarding the sounds and grammar of Gaulish and of Continental Celtic in general.
The Brythonic group includes Breton, Cornish, and Welsh. They are all descendants of British, the Celtic language of the ancient Britons of Caesar's day. The emergence of Welsh, Cornish, and Breton from British as separate languages probably took place during the 5th and 6th cent. A.D. and was a result of the Germanic invasions of Britain. Welsh and Breton have discarded the originally numerous Indo-European cases for the noun and use only one case. Both employ the Roman alphabet for writing. The accent in Welsh and Breton generally falls on the next-to-last syllable, with the exception of a single Breton dialect that has the accent on the last syllable.
Breton today is spoken by more than 500,000 people in Brittany, most of whom are bilingual, speaking also French. It is not surprising that Breton, unlike Welsh, has many loan words from French. Breton is by no means descended from ancient Gaulish, but rather from the Celtic dialects taken by Welsh and Cornish immigrants from the British Isles who were fleeing Germanic invasions and found refuge in Armorica (now French Brittany) in the 5th and 6th cent. A.D. Surviving literary documents in Breton go back only as far as the 15th cent., but the earlier stages of the language are known through glosses and proper names (see Breton literature).
Cornish, the Celtic language of Cornwall, has survived since the late 18th cent. only among bilingual speakers, but it experienced a minor revival in the 20th cent. Estimates of the number of fluent speakers range from a few hundred to a few thousand. Cornish proper names in manuscripts of the 10th cent. A.D. are the oldest recorded traces of the language. A number of Cornish place-names survive, and some Cornish words appear in the English spoken in Cornwall today. The Cornish language is written in the Roman alphabet. It is not noted for an outstanding literature (see Cornish literature).
Welsh (called Cymraeg or Cymric by its speakers) is the language today of over 600,000 people, chiefly in Wales (a western peninsula of Great Britain) but also in the United States and Canada, to which a number of Welsh people have migrated. Most speakers of Welsh in Great Britain also use English. The oldest extant Welsh texts are from the 8th cent. A.D. (see Welsh literature).
The third group of the Celtic subfamily is Goidelic, to which Irish (also called Irish Gaelic), Scots Gaelic, and Manx belong. The term Erse is used as a synonym for Irish and sometimes even for Scots Gaelic. All the modern Goidelic tongues are descendants of the ancient Celtic speech of Ireland. It is thought that the Celtic idiom first came to Ireland shortly before the Christian era. An official language of Ireland, Irish is spoken natively by approximately 75,000 people; roughly a third of Ireland's population can speak and understand it to some degree. Most speakers of Irish also use English (see Irish language).
Scots Gaelic is the tongue of about 60,000 persons in the Highlands of Scotland and an additional 3,000 in Canada. Most of these people also speak English. Gaelic speech began to reach Scotland in the late 5th cent. A.D., when it was brought by the Irish invaders of that country. However, a truly distinctive Scots Gaelic did not appear before the 13th cent. The chief difference between Scots Gaelic and Irish results from the substantial Norse influence on the former. There are four cases for the noun (nominative, genitive, dative, and vocative) in Scots Gaelic, which uses the Roman alphabet (see Gaelic literature).
Manx is a dialect of Scots Gaelic that was once spoken on the Isle of Man, but it has almost entirely died out there. First recorded in writing in the early 17th cent., Manx does not have an important literature. It is written in the Roman alphabet and shows a strong Norse influence.
The rules of pronunciation for all the Celtic languages are extremely complicated. For example, the final sound of a word frequently brings about a phonetically changed initial consonant of the next word, as in Irish fuil, "blood," but ar bhfuil, "our blood." Another example is Welsh pen, "head," but fy mhen, "my head." In order to look up a word in the dictionary, one has to be familiar with these rules of phonetic change, or mutation. There are only two genders in the Celtic languages, masculine and feminine. Words of Celtic origin that have been absorbed by English include bard, blarney, colleen, crock, dolmen, druid, glen, slogan, and whiskey. An interesting feature of Celtic languages is that in several characteristics they resemble some non-Indo-European languages. These characteristics include the absence of a present participle and the use instead of a verbal noun (found also in Egyptian and Berber), the frequent expression of agency by means of an impersonal passive construction instead of by a verbal subject in the nominative case (as in Egyptian, Berber, Basque, and some Caucasian and Eskimo languages), and the positioning of the verb at the beginning of a sentence (typical of Egyptian and Berber).
See H. Lewis and H. Pedersen, A Concise Comparative Celtic Grammar (1937); K. H. Jackson, Language and History in Early Britain (1953); V. E. Durkacz, The Decline of the Celtic Languages (1983); C. W. J. Withers, Gaelic in Scotland, 1698-1981 (1984).
Scholarly handling of the Celtic languages has been rather argumentative owing to lack of much primary source data. Some scholars distinguish Continental Celtic and Insular Celtic, arguing that the differences between the Goidelic and Brythonic languages arose after these split off from the Continental Celtic languages. Other scholars distinguish P-Celtic from Q-Celtic, putting most of the Continental Celtic languages in the former group (except for Celtiberian, which is Q-Celtic).
The Breton language is Brythonic, not Gaulish, though there may be some input from the latter. When the Anglo-Saxons moved into Great Britain, several waves of the native Brythons or "Welsh" (from a Germanic word for "foreigners") crossed the English Channel and landed in Brittany. They brought their Brythonic language with them, which evolved into Breton — which is still partially intelligible with Modern Welsh and Cornish.
In the P/Q classification scheme the first language to split off from Proto-Celtic was Gaelic. It has characteristics that some scholars see as archaic but others see as also being in the Brythonic languages (see Schmidt). With the Insular/Continental classification scheme the split of the former into Gaelic and Brythonic is seen as being late.
The distinction of Celtic into these four sub-families most likely occurred about 900 BCE according to Gray and Atkinson but, because of estimation uncertainty, it could be any time between 1200 and 800 BCE. However, they only considered Gaelic and Brythonic. The controversial paper by Forster and Toth included Gaulish and put the break-up much earlier at 3200 BCE +/- 1500 years. They support the Insular Celtic hypothesis. The early Celts were commonly associated with the archaeological Urnfield culture, the Hallstatt culture, and the La Tène culture, though the earlier assumption of association between language and culture is now considered to be less strong.
There are two main competing schemata of categorization. The older scheme, argued for by Schmidt (1988) among others, links Gaulish with Brythonic in a P-Celtic node, originally leaving just Goidelic as Q-Celtic. The difference between P and Q languages is the treatment of Proto-Celtic *kw, which became *p in the P-Celtic languages but *k in Goidelic. An example is the Proto-Celtic verb root *kwrin- "to buy", which became pryn- in Welsh but cren- in Old Irish. However, a classification based on a single feature is seen as risky by its critics, particularly as the sound change occurs in other language groups (Oscan and Greek).
The other scheme, defended for example by McCone (1996), links Goidelic and Brythonic together as an Insular Celtic branch, while Gaulish and Celtiberian are referred to as Continental Celtic. According to this theory, the "P-Celtic" sound change of [kʷ] to [p] occurred independently or areally. The proponents of the Insular Celtic hypothesis point to other shared innovations among Insular Celtic languages, including inflected prepositions, VSO word order, and the lenition of intervocalic [m] to [β̃], a nasalized voiced bilabial fricative (an extremely rare sound). There is, however, no assumption that the Continental Celtic languages descend from a common "Proto-Continental Celtic" ancestor. Rather, the Insular/Continental schemata usually considers Celtiberian the first branch to split from Proto-Celtic, and the remaining group would later have split into Gaulish and Insular Celtic.
There are legitimate scholarly arguments in favour of both the Insular Celtic hypothesis and the P-Celtic/Q-Celtic hypothesis. Proponents of each schema dispute the accuracy and usefulness of the other's categories. However, since the 1970s the division into Insular and Continental Celtic has become the more widely held view (Cowgill 1975; McCone 1991, 1992; Schrijver 1995).
When referring only to the modern Celtic languages, since no Continental Celtic language has living descendants, "Q-Celtic" is equivalent to "Goidelic" and "P-Celtic" is equivalent to "Brythonic".
Within the Indo-European family, the Celtic languages have sometimes been placed with the Italic languages in a common Italo-Celtic subfamily, a hypothesis that is now largely discarded, in favour of the assumption of language contact between pre-Celtic and pre-Italic communities.
How the family tree of the Celtic languages is ordered depends on which hypothesis is used -
(Irish) Ná bac le mac an bhacaigh is ní bhacfaidh mac an bhacaigh leat.
(Literal translation) Don't bother with son the beggar's and not will-bother son the beggar's with-you.
(Welsh) pedwar ar bymtheg a phedwar ugain
(literally) four on fifteen and four twenties