On Generation and Corruption (Περὶ γενέσεως καὶ φθορᾶς; De Generatione et Corruptione), also known as On Coming to Be and Passing Away is a treatise by Aristotle. Like many of his texts, it is both scientific, part of Aristotle's biology, and philosophic. The philosophy is essentially empirical; as in all of Aristotle's works, the inferences made about the unexperienced and unobservable are based on observations and real experiences. The question raised at the beginning of the text builds on an idea from Aristotle's earlier work The Physics. Namely, whether things come into being through causes, through some prime material, or whether everything is generated purely through "alteration." Alteration concerned itself with the ability for elements to change based on common and uncommon qualities. From this important work Aristotle gives us two of his most remembered contributions. First, the Four Causes and also the Four Elements (earth, wind, fire, and water). He uses these four elements to provide an explanation for the theories of other Greeks concerning atoms, an idea Aristotle considered absurd. The work is connected with De Caelo and Meteorology, and plays a significant preparatory role to the biological and physiological texts. Among the primary themes is an investigation of physical contraries (hot, cold, dry, and moist) and the sorts of processes and types of composition that they form in nature and biology. The theory put forward is meant to secure its position by elucidation the meaning of agent and patient, contact, process of generation, alteration, mixture, all things which his predecessors had failed to understand. It is thus, in some ways, more similar to the Physics, which is more general, clarifying the general notions of change, cause, matter, and form. It has not moved fully into an applied investigations found in the above mentioned scientific texts. Classical element#Aristotle Aristotle outlined the types of change in Categories and Physics.