The term ‘idea’ traverses the depth-psychology corpus along several distinct axes, each carrying its own epistemic weight. Jung, in Psychological Types, offers the most technically precise definition: the idea is the abstracted meaning of a primordial image—collective yet lacking mythological visual quality, a product of thought derived from the image rather than identical with it. This situates the idea as a conceptual precipitate of the archetype, downstream from image and upstream from pure abstraction. Hillman radically revalues this inheritance: for him, ideas are not merely cognitive events but ontological modes through which soul enacts and envisions life. The soul requires its own ideas, and soul-making proceeds as much through ideation as through feeling or relationship. Against the pragmatist reduction—where an idea’s worth is measured by its immediate applicability—Hillman insists that the conversion of an idea into practice kills its generative force, its logos spermatikos. Aurobindo offers yet another pole: in Supermind, the idea is not an abstraction from being but luminous power indistinguishable from being itself, a Real-Idea in which knowing, willing, and existing remain undivided. Descartes and Plato provide the classical philosophical backdrop against which all these positions maneuver. Von Franz and Giegerich extend the Jungian position: every fruitful scientific theory rests on an archetypal idea, and soul at its deepest is logical life, Notion—with ideas as the hidden content within symptom, emotion, and image alike. The central tension across the corpus is between idea as abstraction (cognitive, derived, secondary) and idea as psychic-ontological reality (generative, soul-constitutive, even divine).