Dunamis — the Greek term for capacity, potentiality, or power — enters the depth-psychology and philosophical-psychology corpus at a critical intersection between ontology, character theory, and the metaphysics of action. The major axis of discussion runs from Aristotle’s tripartite division of soul-states into pathē, dunameis, and hexeis, through Stoic reformulations of psychic powers, to Ricoeur’s phenomenological reappropriation of act and potency as foundational categories for the self. In Aristotle, as reconstructed by Cairns and confirmed by the De Anima glossary, dunamis designates the neutral capacity to undergo or exhibit a quality — prior to and distinct from the stable disposition (hexis) that emerges through habituation. The Stoics, as Inwood demonstrates, recast dunameis as real, physically grounded dispositions within the governing mind (hēgemonikon), bringing the term into direct contact with impulse theory and the ethics of action. Vernant’s reading of early Greek cosmology illuminates a pre-philosophical register in which dunamis names a domain-bounded cosmic power, contained and defined by its limits. Ricoeur synthesises these threads, insisting that the Aristotelian dyad of act and power constitutes a metacategory indispensable for any ontology of the acting self. The central tension across the corpus is whether dunamis names a merely formal capacity, an innate tendency, or an already-organised disposition with ethical weight.