Chronology of Thomas de Hartmann's life and major musical works

From May 1923 to June 1927, Gurdjieff and de Hartmann composed, in a collaboration unique in the history of music, the orchestral pieces for the Movement Demonstrations in 1923 and 1924 as well as many compositions for piano solo. In 1922, de Hartmann accepted a job as director of the music-publishing company Belaieff and, as a further effort to raise money both for himself and for the Gurdjieff household, started to write music for films under the pseudonym Thomas Kross. By 1936, when he stopped this activity, he had written the music for 52 films.
The de Hartmanns travelled with Gurdjieff on his journeys to America in 1924 and 1929. In that last year, de Hartmann left Gurdjieff, never to see him again, but his faith in his teacher remained unaltered. From then on, he worked on his own music, in which Gurdjieff's influence is not discernible.
In 1935, he finished his first symphony, opus 50, which was performed later in Paris and Brussels, as well as his Cello Concerto, opus 57, which was performed by Pablo Casals and the Boston Symphony Orchestra. His Violin Sonata, opus 51 was published in 1937.