The ‘change’ attributed to a thing (in the sense of ‘progress’ or ‘transition’ from one state to another) may be (1) incidental to the change of something else with which it is connected, or (2) may be transferred in our parlance from the part to the whole, or (3) may be attributable in its proper sense to the thing in its entirety. And when the change can be thus properly and integrally attributed to the thing, we must further distinguish between the several kinds of ‘transition.’ It may, for instance, be not local (a change of place) but qualitive (a change of quality), and again subvarieties of qualitive change may be distinguished (224 a 21–30).
This all applies to the agent of the change as well as to the subject that undergoes it (a 30–34).
Moreover, in addition to the proper and integral cause and subject of the change, we must consider the time in which the change takes place and the conditions from which, and to which, the thing that experiences the change passes. This last point is important. If a bar of cold iron is heated, it is not heat or coldness that changes, but the iron that changes or passes from cold to hot. And it is after the point to which it tends, not that from which it recedes, that the change or transition is named: the bar ‘grows hot’ or ‘tends heat-
Chapter IArgument (continued)
wards.’ We have already examined the nature of ‘movement’ (in its extended sense, including ‘modification’ and ‘expansion or contraction’) and have now to note that ‘shape’ and ‘state’ and ‘place’ are the ‘whence’ and ‘whither’ of change, hut are immovable in themselves (a 34–b 16).
It is important, however, to note that these immovable points of starting and arriving are just as subject to the distinctions of ‘incidental,’ in virtue of a part,’ and 4 primary and integral,’ as the movements are (b 16–22).
Summary (b 22–26).
Dismissing the indeterminate incidental cases and confining ourselves to proper and primary ‘changes,’ we note that they reside solely in the primary and integral subject that experiences the change, and must be in the direction from one opposite to the other, both opposites being declared in positive (not negative) terms (b 26–35).
This last point must be elaborated. To speak of the ‘not-hot’ as the primary and integral ‘subject’ that undergoes the change would be idle. For ‘knowledge,’ or ‘sound’ or ‘angularity’ are ‘not-hot’; and though ‘not–hotness’ may incidentally undergo change when any of these things