ABSTRACT
A dynamic understanding of the universe was the goal of astronomers and physicists working in the Aristotelian tradition. Indeed, the standard interpretation of Aristotle's work is that he began very close to Plato's intellectual position and only gradually departed from it. Aristotle continually analyzed and classified, as if what were necessary to understand a subject was to divide it into categories. To understand Aristotle's cosmology, it is necessary first to understand his physics. Aristotle frequently explained a thing in terms of its purpose. The one form of locomotion that could be continuous is discussed by Aristotle in the last book of his Physics. Thus beginning with that which he disputed, that the world was infinite, and showing that the premise led to an absurd conclusion, Aristotle by the method of reductio ad absurdum proved the opposite.
