What is the last name of the composer that aroused religious philosophy interest in the man who was fascinated with Celtic languages?
By April 1917 Heseltine had again tired of London life. He returned to Cornwall where he rented a small cottage near the Lawrences, and made a partial peace with the writer. By the summer of 1917, as Allied fortunes in the war stagnated, Heseltine's military exemption came under review; to forestall a possible conscription, in August 1917 he moved to Ireland, taking Puma, with whom he had decided he was, after all, in love.In Ireland Heseltine combined studies of early music with a fascination for Celtic languages, withdrawing for a two-month period to a remote island where Irish was spoken exclusively. Another preoccupation was an increasing fascination with magical and occult practices, an interest first awakened during his Oxford year and revived in Cornwall. A letter to Robert Nichols indicates that at this time he was  "tamper[ing] ... with the science vulgarly known as Black Magic". To his former tutor Colin Taylor, Heseltine enthused about books "full of the most astounding wisdom and illumination"; these works included Eliphas Levi's History of Transcendental Magic, which includes procedures for the invocation of demons. These diversions did not prevent Heseltine from participating in Dublin's cultural life. He met W.B. Yeats, a fellow-enthusiast for the occult, and briefly considered writing an opera based on the 9th-century Celtic folk-tale of Liadain and Curithir. The composer Denis ApIvor has indicated that Heseltine's obsession with the occult was eventually replaced by his studies in religious philosophies, to which he was drawn through membership of a theosophist group in Dublin. Heseltine's interest in this field had originally been aroused by Kaikhosru Sorabji, the composer who had introduced him to the music of Béla Bartók.On 12 May 1918 Heseltine delivered a well-received illustrated lecture, "What Music Is", at Dublin's Abbey Theatre, which included musical excerpts from Bartók, the French composer Paul Ladmirault, and Van Dieren. Heseltine's championing of Van Dieren's music led in August 1918 to a vituperative war of words with the music publisher Winthrop Rogers, over the latter's rejection of several Van Dieren compositions. This dispute stimulated Heseltine's own creative powers, and in his final two weeks in Ireland he wrote ten songs, which later critics have considered  to be  among his finest work.
Sorabji