MacDowell's teachers in theory were Savard, at the Paris Conservatoire, and Joachim Raff, in Frankfurt, and in piano, at these places respectively, Marmontel and Heyman. An interim was spent with Ehlert in Wiesbaden. Franz Liszt was MacDowell's friend and helped him to recognition in Germany. No American composer has been so prominent as MacDowell as a concert pianist. His sensitive performances of his own works served to make them broadly known and to establish the traditions of their interpretation. The composer took up his residence in America again in 1888, after twelve years of absence, first in Boston, and later in New York, where, until his unfortunate friction with the academic authorities, he exerted a wide influence as professor of music at Columbia University. The malady which alienated him from his powers in his last years, and which finally brought about his end, called universal attention to America's musical awakening and prowess by the same stroke in which it removed the nation's musical leader. MacDowell attained his chief critical recognition through his two concertos and four sonatas for piano. The second concerto, in D minor, with its alternate phases of nobility and charm, stands as a monument to the composer's highest powers, with regard both to pianistic and orchestral mediums of expression. The composer's harmonic warmth and individuality, his freshness of melodic inspiration, his marked capacity for skillful and colorful orchestration, his eager and highly pitched temperament, are all manifest throughout the work. Of the four sonatas, the 'Tragica,' 'Eroica,' 'Norse,' and 'Keltic,' the last has been universally judged the greatest, and one of his greatest works. Lawrence Gilman calls it his 'masterpiece.' As their titles indicate, these works are all programmatic, though not slavishly so, and romantic in the highest degree. Their material, derived from the rich storehouse of Gaelic legend, finds the composer on his native spiritual heath, and in them he speaks with an authority not surpassed, perhaps not equalled, in the whole range of his work beside.