Combined in this volume are two works by Aristotle, "On the Heavens" and "On Generation and Corruption". The first work, "On the Heavens" is Aristotle"s cosmological treatise, in which Aristotle details his astronomical theories. The second work, "On Generation and Corruption", is a work of science philosophy. Building upon his arguments in "Physics", Aristotle poses the question as to whether or not the act of something coming into being is the result of a specific cause or merely the result of the inevitable change in a world that is constantly in motion.