the Dionysian ekstasis comes in.... In one of his letters to his sister he gives a most impressive description of the ekstasis in which he wrote Zarathustra.... He says about his way of writing that it simply poured out of him, it was an almost autonomous production
Edinger, reading Jung on Nietzsche, identifies the composition of Zarathustra as paradigmatic Dionysian ekstasis: creative work experienced as autonomous production erupting through, rather than from, the subject.
, Science of the Soul: A Jungian Perspective, 2002thesis