Having thus glanced briefly at the representatives of the older scholarship and their work, we shall now have occasion to retrace our steps to consider the representatives of the new critical and philological movement. After Edward Lhuyd’s demise no further progress seems to have been registered in the elucidation of Celtic philology till the time of Franz Bopp. Even as late as the first quarter of the nineteenth century, Gaelic was regarded by scholars as a peculiar language, unconnected with the other European tongues. It is true that Sir William Jones, from his study of Sanskrit, had thrown out the hint as early as 1786, that Celtic was of the same original stock with the other languages of Europe and South-Western Asia; but when Bopp first published his _Comparative Grammar_ Celtic was omitted. It was Dr. Pritchard, an English ethnologist, who, in 1832, really demonstrated on the lines laid down by Grimm and Bopp, that the Celtic language is a member of the Indo-European group. His book, entitled _The Eastern Origin of the Celtic Nations_, from this time drew the attention of continental scholars to the excluded and hitherto neglected language, with the result that three important works soon after appeared, namely, first, one _On the Affinity of the Celtic Languages with the Sanskrit_, by Adolph Pictet (Paris, 1837); second, the _Die Celtischen Sprachen_, or _Celtic Philology_, by Bopp (Berlin, 1839); and the _Celtica_ of Dr. Diefenbach (Stuttgart, 1839–40). By this time Bopp had studied the Celtic dialects, and published the above work as a supplement to his great _Comparative Grammar of the Sanskrit, Zend, Greek, Latin, Lithuanian, Gothic, German, and Sclavonic Languages_. Some features of Gaelic phonetics, such as initial aspiration and ellipsis, taking the place of declension, seems hitherto to have baffled scholars, but Bopp’s sagacity enabled him to perceive that these are nothing else than the relics and results of the after-action of the old case-endings, and that the rational explanation is to be found in the final sound of the previous word, or, as we now say, vocalic and nasal auslaut. This discovery has since been fully confirmed by Zeuss, Ebel, and Windisch. It was with the publication of the _Grammatica Celtica_, however, that the great moment in the evolution of Celtic scholarship arrived. Its gifted author, J. Caspard Zeuss, stands supreme as the real founder of Celtic philology. He did for it what Grimm did for the Teutonic, and Diez for the Romance. Since the appearance of his monumental work it has been definitely settled that the Celtic languages are pure Indo-European tongues, without any admixture of foreign elements, and thus that they are members of the family in the same sense that Latin or Gothic is. In addition, it has furnished the means of interpreting the most ancient forms of the Gaelic language found in the very old MSS., which before then had defied the efforts of translators.