In philosophy, potentiality and actuality are a pair of closely connected principles which Aristotle used to analyze motion, causality, ethics, and physiology in his Physics, Metaphysics, Nicomachean Ethics, and De Anima. The concept of potentiality, in this context, generally refers to any "possibility" that a thing can be said to have. Aristotle did not consider all possibilities the same, and emphasized the importance of those that become real of their own accord when conditions are right and nothing stops them. Actuality, in contrast to potentiality, is the motion, change or activity that represents an exercise or fulfillment of a possibility, when a possibility becomes real in the fullest sense. These concepts, in modified forms, remained very important into the Middle Ages, influencing the development of medieval theology in several ways. In modern times the dichotomy has gradually lost importance, as understandings of nature and deity have changed. However the terminology has also been adapted to new uses, as is most obvious in words like energy and dynamic. These were words first used in modern physics by the German scientist and philosopher, Gottfried Wilhelm Leibniz. Aristotle's concept of entelechy retains influence on recent concepts of biological "entelechy". Potentiality "Potentiality" and "potency" are translations of the Ancient Greek word (δύναμις). They refer especially to the way the word is used by Aristotle, as a concept contrasting with "actuality". The Latin translation of dunamis is , which is the root of the English word "potential"; it is also sometimes used in English-language philosophical texts. In early modern philosophy, English authors like Hobbes and Locke used the English word power as their translation of Latin . is an ordinary Greek word for possibility or capability. Depending on context, it could be translated 'potency', 'potential', 'capacity', 'ability', 'power', 'capability', 'strength', 'possibility', 'force' and is the root of modern English words dynamic, dynamite, and dynamo. In his philosophy, Aristotle distinguished two meanings of the word . According to his understanding of nature there was both a weak sense of potential, meaning simply that something "might chance to happen or not to happen", and a stronger sense, to indicate how something could be done well. For example, "sometimes we say that those who can merely take a walk, or speak, without doing it as well as they intended, cannot speak or walk". This stronger sense is mainly said of the potentials of living things, although it is