Meyer was considered first and foremost a lexicographer among Celtic scholars but is known by the general public in Ireland rather as the man who introduced them to Selections from Ancient Irish Poetry (1911).

[1][2] He founded and edited four journals devoted to Celtic Studies,[2] published numerous texts and translations of Old and Middle Irish romances and sagas, and wrote prolifically, his topics ranging to name origins and ancient law.

In October 1911, he followed Heinrich Zimmer as Professor of Celtic Philology at Friedrich Wilhelm University in Berlin; the following year, a volume of Miscellany was presented to him by pupils and friends in honour of his election, and he was made a freeman of both Dublin and Cork.

[a][11] A pro-German speech he gave in December 1914 to Clan na Gael on Long Island caused outrage in Britain and some factions among the Irish, and as a result, he was removed from the roll of freemen in Dublin and Cork and from his Honorary Professorship of Celtic at Liverpool.

However, when the April 1915 issue of The Harvard Advocate awarded first prize to an anti-German satirical poem "Gott mit Uns" written by an undergraduate, Meyer sent the university (and the press) a letter of protest, rebuking the faculty members who served as judges for failure to exercise neutrality.

In a reply, President Abbott Lawrence Lowell said, in explaining Harvard's policy, that freedom of speech includes pro-German and pro-Allied voices alike.

The restoration happened on 19 April 1920 in Dublin, where Sinn Féin had won control of the City Council three months before, rescinding the decision taken in 1915 by the Irish Parliamentary Party.

Hyde credited him with advancing the goals of the Gaelic League when the question arose whether to allow the teaching of the Irish language in the Intermediate Education of Ireland.