4. Fourth Way

46. [Exposition of the opinion] - He who would maintain the conclusion of these reasons [nn.41-45] could negate of habit all idea of active principle, and say that a habit only gives an inclination to operation as a sort of prior act agreeing with second act and giving a determination to that act - just as heaviness is a prior act, giving determination and inclination to a determinate ‘where’, although, according to some, heaviness is not a principle with respect to existing in that ‘where’.

47. [Approval of the opinion] - And this opinion seems probable, because to nothing should causality with respect to anything be attributed unless such causality is evident from the nature of the things (whether of the cause or of the thing caused); also to no cause should perfect causality be denied unless imperfection of causality appears manifestly in it, because no nature should be denied to possess a perfection which it does not evidently lack. But there seems to be no necessity of positing any active causality in the habit with respect to the act, because without this all the conditions commonly attributed to the habit will be saved [n.48]; also there is no necessity to take away from the power the perfect idea of causality so as to attribute a partial causality to the power. Therefore there is no need to attribute any causality to the habit.

48. The assumption is plain, because the four conditions that are attributed to the habit, namely that it is ‘that whereby the possessor of it operates easily, with pleasure, without impediment, and promptly’ [n.7], are saved by the habit’s inclination alone, which the habit attributes to the power as the power is receptive of operation.

49. Pleasure indeed exists because of the condition of the receiver, to whom belongs the operation received and the object about which the operation is. For pleasure is never in a making that is precisely a making, but because action is in the agent action can be pleasant because of the agreement of the agent with the object; but this agreement can be provided by the habit from the fact that it gives an inclination toward the action and the object. Pleasurability, therefore, does not include the idea of active principle, but only the agreement of the passive principle with the power and the object, and that as to action which is of the genus of quality, not action which is of the genus of action, - which difference in actions was stated above in distinction 3 [I d.3 nn.600-604]. Operation indeed is an action that is a quality, and it belongs to an habituated power that is, by the habit, inclined to such an act and to the object that terminates such an operation; but it does not thus belong to a non-habituated power, nor does such a form or such an object so belong.

50. Likewise as to the second condition. Difficulty in operation occurs from the fact that what is receptive of the operation is not disposed to receiving it, and not merely from a defect in the active virtue; therefore if what is receptive is disposed, there will be easiness in acting, to the extent the agent acts on such a receptive thing.

51. Likewise about absence of impediment and promptness. For impediment to, and slowness of, the agent in acting can be because of the indisposition of the receptive thing itself, especially when the same thing is agent and recipient, so that it will not itself operate promptly because it is indisposed to operating. This indisposition, then, is not for performing an action in the genus of action, but for having an action in the genus of quality; for nothing is said formally to operate insofar as it elicits operation but insofar as it receives it in itself.

52. Also, the way that the other things commonly attributed to a habit are saved, by attributing the whole action to the power and no activity to the habit, will be plain from solving the arguments to the principal point [nn.6-7, 12-14, 87-91].