In Kleinian theory unconscious phantasies underlie every mental process and accompany all mental activity. They are the mental representation of those somatic events in the body that comprise the instincts, and are physical sensations interpreted as relationships with objects that cause those sensations. Freud introduced the concept of unconscious phantasy and phantasising, which he thought of as a phylogenetically inherited capacity of the human mind. Klein adopted his idea of unconscious phantasy but broadened it considerably because her work with children gave her extensive experience of the wide-ranging content of children's phantasies.