Thomas Hobbes then, the traditional Aristotelian terms, "", are discussed, but he equates them simply to "cause and effect". There was an adaptation of at least one aspect of Aristotle's potentiality and actuality distinction, which has become part of modern physics, although as per Bacon's approach it is a generalized form of energy, not one connected to specific forms for specific things. The definition of energy in modern physics as the product of mass and the square of velocity, was derived by Leibniz, as a correction of Descartes, based upon Galileo's investigation of falling bodies. He preferred to refer to it as an or 'living force' (Latin ), but what he defined is today called kinetic energy, and was seen by Leibniz as a modification of Aristotle's , and his concept of the potential for movement which is in things. Instead of each type of physical thing having its own specific tendency to a way of moving or changing, as in Aristotle, Leibniz said that instead, force, power, or motion itself could be transferred between things of different types, in such a way that there is a general conservation of this energy. In other words, Leibniz's modern version of entelechy or energy obeys its own laws of nature, whereas different types of things do not have their own separate laws of nature. Leibniz wrote: ...the entelechy of Aristotle, which has made so much noise, is nothing else but force or activity ; that is, a state from which action naturally flows if nothing hinders it. But matter, primary and pure, taken without the souls or lives which are united to it, is purely passive ; properly speaking also it is not a substance, but something incomplete. Leibniz's study of the "entelechy" now known as energy was a part of what he called his new science of "dynamics", based on the Greek word and his understanding that he was making a modern version of Aristotle's old dichotomy. He also referred to it as the "new science of power and action", (Latin and ). And it is from him that the modern distinction between statics and dynamics in physics stems. The emphasis on in the name of this new science comes from the importance of his discovery of potential energy which is not active, but which conserves energy nevertheless. "As 'a science of power and action', dynamics arises when Leibniz proposes an