Page - 93 - in The Priority of Locomotion in Aristotle’s Physics

corruption of the four elements take place in virtue of aggregation and seg- regation. Although it is wrong to say that this is all that happens when one of the elemental bodies comes to be or perishes, and that this process may be reduced to nothing but aggregation or segregation, one has to have in mind that substantial change in GC I 2 is described as a change in the form or definition (λόγος), but also in the matter (ὕλη) of the underlying thing.51 I take it that Aristotle applies the concepts σύγκρισις and διάκρι- σις, terms coined by his predecessors, in order to refer to processes that occur on the material level and are an essential part of the elemental bodies’ generation and corruption, but also, as I will show, of any other substance’s generation and corruption. That Aristotle views these concepts as playing such a significant role in understanding substantial change is also supported by a statement made in GC I 2, where it is stated that something which undergoes aggregation or a segregation becomes more or less susceptible to corruption as a result.52 However, the occurrence of aggregation or segrega- tion does not necessarily bring about a substantial change: heating a portion of water, for instance does not have to lead to the corruption of the portion of this element, although the heating, as we have seen in the examples from the Meteorology involves segregation of the water, which is manifested in an increase in the water’s volume. But if water is heated long enough, then it will perish at some point due to the fact that it has undergone a segregation and no longer has the form of water, i.e. is no longer characterized by its specific combination of the basic qualities of cold and wet and by its motion towards its sphere.53 Therefore, undergoing either segregation or aggrega- tion is not a sufficient condition for an element to undergo generation or corruption. Nevertheless, these two processes are obviously an essential part of what happens when elemental bodies come to be or perish. In this way, i.e. with respect to the elements, Aristotle in Phys. VIII 7 correctly says that we speak of generation and corruption in virtue of σύγκρισις and διάκρι- σις, since the occurence of one of the two is a necessary condition for the occurence of either of the former two processes. But, this of course, does perishing of air, which Aristotle describes as a process of aggregation see for example Mete. I 3, 341a4 and 341a9–10. For the reverse process and the change from air to fire, i.e. the com- ing to be of fire and the corruption of air, which occur by means of segregation, see Mete. I 3, 340a8–10 and 340b3. 51 See GC I 2, 317a23–24. I take it that the reason why Aristotle mentions the material aspect of a substantial change here in GC while he usually neglects it in other characterisa- tions of change in substance is that he focuses on what happens on what one might call the material level. 52 See GC I 2, 317a27–29. 53 For the characterisation of the elements by the pairs of qualities of hot-cold and dry- moist see GC II 3, 330b3–7. What undergoes generation or corruption changes with respect to place 93 ISBN Print: 9783525253069 — ISBN E-Book: 9783647253060 © 2014, Vandenhoeck & Ruprecht GmbH & Co. KG, Göttingen