Glass composed the Fourth Symphony, in E minor, op. 43, in 1911, ten years after the Forest Symphony and in the middle of the period when he was also directing the Danish Concert Association. It stands between the nature poetry of the Third and the theosophical preoccupations that shaped the Fifth and Sixth: Glass had by then joined the Theosophical Society, and the later symphonies take their titles and their programmes from that world. The idiom remains late Romantic, with Bruckner's proportions and Franck's habit of carrying themes between movements.