But that common mother-tongue at the remote period in question, the period of the earliest occupancy of Britain, must have been spoken on both sides of the Channel--in Gaul as well as the British Islands. And here (_i.e._, in Gaul) it may have done one of two things. It may have remained unaltered; or, it may have undergone change. Now in either case it would be different from both the Gaelic and the British. In the former alternative it would have been stereotyped as it were, and so have preserved its original characters, whilst the Gaelic and British had adopted new ones. In the latter it would have altered itself after its own peculiar fashion; and those very peculiarities would have made it other than British as well as other than Gaelic. Yet what is the fact? The ancient language of Gaul, though as unlike the Gaelic as a separate and independent development was likely to make it, was _not_ unlike the British. On the contrary, it was sufficiently like it to be intelligible to a Briton. Now I hold this similarity to be conclusive against the doctrine that the British and Gaelic languages were developed out of some common mother-tongue _within the British Islands_. Had they been so the dialects of Gaul would have been far more unlike the British than they were. The _British_ then, at least, did not acquire its British character in Britain, but on the continent; and it was introduced into England as a language previously formed in Gaul. For the Gaelic there is no such necessity for a continental origin; indeed at the first view, the probabilities are in favour of its having originated in Britain. It cannot be found on the continent; and, such being the case, its continental origin is hypothetical. One thing, however, is certain, viz., that if the Gaelic were once the only language of the British Isles, the conquests and encroachments of the Britons who displaced it, must have been enormous. In the whole of South Britain it must certainly have been superseded, and in half Scotland as well: whilst, if, before its introduction into Great Britain, it were spoken on any part of the continent, the displacement must have been greater still. Now, the hypothesis as to the origin of the Gaels may take numerous forms. I indicate the following three.--