The uniformity that presents itself in the ancient local nomenclature of all the Celtic countries is a very remarkable and instructive feature, of which an adequate conception can be formed only by an examination of the Roman Maps. The identity of names, for example, is found to be as complete when the Roman Maps of Gaul and Britain are compared, as we meet with in examining the Maps of two English Counties! To this rule Ireland, as far as we can judge from the imperfect nature of the information transmitted to us, formed no exception. These facts lead to the inference that the Celts must have diffused themselves, within a comparatively short interval of time, over all the regions of Europe of which the Romans found them in possession! Had the process of diffusion occupied a great many ages, there must have been a commensurate change in the Celtic language, which would have displayed itself in the local names of the more distant regions. But no such difference occurs, the local nomenclature of Britain, for instance, being identical with that of Switzerland and Spain! SECTION VI. _Summary of the Results deducible from the previous Sections. The Changes which have occurred in the English, Scandinavian, and Celtic Languages, sufficient to account for the Differences among all Human Tongues. Causes which give rise to the Abandonment and specific Appropriation of Synonymes. Total Differences of Grammatical Forms no Proof of a fundamental Difference of Language. The Relation which the Languages of one Continent, viewed in the aggregate, bear to the individual Languages of such Continent, the same as that which the ancient Scandinavian bears to its derivative Dialects, &c. Incipient Changes in the Language of Australia._ The facts developed in the previous Sections obviously present a satisfactory solution of the problem suggested at page 25, viz., whence it has come to pass that languages almost totally different in their present composition could have sprung from one original Tongue? That existing languages have sprung from one source is a proposition of which the proofs have been explained in the same Chapter in which this problem has been suggested. (See Chap. I.) In the preceding Sections it has been shown, agreeably to the statement contained in Section I., that Languages are exposed to two prominent causes of change; viz., the abandonment by different branches of the same race—1, of different Synonymes; 2, of different meanings of the same Synonyme.