The night side of the soul Influences from romanticism and natural philosophy in the work of C.G. Jung in the context of the history of ideas of the 19th century (by Doaa Moustafa) The present work investigates the “roots” of the “Complex Psychology”, which was founded by the Swiss psychologist C.G. Jung, in the history of ideas. At first, the tremendous influence of the romantic Weltanschauung as well as of the notions which characterised the idealism of the 19th century exerted upon the Jung is shown. It is illustrated that he drew on the teachings of E. von Hartmann about the unconscious, but was also influenced by natural philosophers C.G Carus and G.H. von Schubert. Equally, Jung dealt with the teachings of philosophers of religion like F.W. Schelling and R. Otto and remodelled them according to this own Weltanschauung. Jung also dealt with phenomena like somnambulism and mesmerism. Hence, he took a critical stance towards the teachings of the rational Enlightenment and positivism. This rather idealistic approach led to a rupture with S. Freuds psychoanalysis, who took a naturalistic stance. The second part of the work at hand deals in detail with the approaches of some 19th century-natural philosophers. For C.G. Jung assumed that mind and nature, animus and anima, the individual and society constitute a basic original unity. Therefore, according to Jung, life is characterised by androgyny. In myths and in the rites of religion but first and foremost in dreams he saw evidences for the “night side” of the human soul. In the experience of the ground of the soul he followed the language of the mystics (Meister Eckhart). Furthermore, attention is drawn to the insights of modern brain research which deal with the creation of mental images in the human brain (G. Hüther). Thereby, the present work intents to show that some notions coined by C.G. Jung also have some relevance in empirical research.