dunamis also dynamis (Greek, ‘power’, ‘capacity’), as used by pre-Socratics such as Anaximander and Anaxagoras, one of the elementary character-powers, such as the hot or the cold, from which they believed the world was constructed. Plato’s early theory of Forms borrowed from the concept of character-powers as causes present in things; courage, e.g., is treated in the Laches as a power in the soul. Aristotle also used the word in this sense to explain the origins of the elements. In the Metaphysics (especially Book IX), Aristotle used dunamis in a different sense to mean ‘potentiality’ in contrast to ‘actuality’ (energeia or entelecheia). In the earlier sense of dunamis, matter is treated as potentiality, in that it has the potential to receive form and so be actualized as a concrete substance. In the later Aristotelian sense of dunamis, dormant abilities are treated as potentialities, and dunamis is to energeia as sleeping is to waking, or having sight to seeing. See also ARISTOTLE , ENERGEI. P.Wo.