His 1886 thesis, Evolução da linguagem (Evolution of Language) demonstrated an early interest that would come to occupy all his long life.

At the University of Paris, he completed a doctoral thesis, Esquisse d'une dialectologie portugaise (1901), the first important compendium of Portuguese dialects (work that was later continued and advanced by Manuel de Paiva Boléo and Luís Lindley Cintra).

In 1902 he published an article ("Vozes galhegas") in the journal Revista Lusitana, based on a manuscript entered into the National Library of Madrid sometime after 1843.

Despite his enormous talent and immense capacity for scholarship, perhaps he spent too much time on his other research and writing to avoid pitfalls on his Galician work.

At the dawn of the 20th century a golden opportunity was lost, therefore, of applying the scientific precision of historical linguistics, in the hands of an authentic philologist, to the analysis of the Galician language.