Seite - 109 - in The Priority of Locomotion in Aristotle’s Physics

comitant with this change, however, is the water’s change in density, for a smaller portion of earth arises from a larger portion of water. As we have seen with respect to the change from water to air, this seems to be true in general for any process of transformation from one kind of element to another, since the difference in size between the portion of the perishing element and the portion of the element that has come to be occurs without any additional matter being added and thus is a process of either condensa- tion or rarefaction as described in Phys. IV 9.103 Accordingly, any change from one element to another involves a change in density, as the change in size cannot be explained otherwise. That this must be what happens becomes clear in another way. We saw in the previous section that any transformation of an element into another always occurs in virtue of aggregation (σύγκρισις) or segregation (διάκρι- σις). Therefore, when for example earth is turned into water, or fire into air —in each case a change from dry to wet taking place—aggregation or segre- gation of the elemental bodies are necessarily involved in both processes.104 As I will have to show later on105, the aggregations and segregations that occur when elements are being transformed are processes of condensation and rarefaction, i.e. changes in the respective thing’s density. Thus, it is clear that of the two basic pairs of qualities, not only a change with respect to hot-cold, but also to dry-moist always corresponds to a change in the density of that which is affected. As we have seen above, any alteration necessarily involves a change with respect to the four basic qualities of hot-cold and dry-moist. In addition it has just become clear that every change with respect to these four basic qua- lities, again, goes hand in hand with condensation or rarefaction, i.e. a change in density. Therefore, one is justified in inferring that any change in quality—in virtue of involving a change with respect to the four basic quali- ties—also requires the occurrence of either a πύκνωσις or a μάνωσις, that is, a change in density. This then is the sense in which the processes of condensation and rare- faction may be seen as sources of all other qualities: all kinds of qualities 103 In the example from Phys. IV 9 a larger portion of air comes to be from a smaller one of water. The water changes in size without any additional stuff being added (see 214b1–2). That πύκνωσις and μάνωσις always go hand in hand with a change in quantity is also clear from the way they are characterised in the discussion of Phys. IV 9. If condensation and rare- faction for Aristotle did not imply a change in size of their respective subject, there would be no reason for Aristotle’s opponent to claim that only the existence of the void can explain why the universe does not bulge, nor for Aristotle to discuss this problem in the way he does (See Phys. IV 9). 104 See for instance Mete. I 3, 340a8–10, where the change from air to fire is described as a process of segregation. 105 See section 4.4.5. What changes in quality changes with respect to place 109 ISBN Print: 9783525253069 — ISBN E-Book: 9783647253060 © 2014, Vandenhoeck & Ruprecht GmbH & Co. KG, Göttingen