Metaphysics

​For the work is the end, and the actuality is the work; wherefore even the name ‘actuality’ is said in relation to ‘work’ and points toward ‘complete reality’ (entelechy). And since in some cases the ultimate thing is the use (as seeing is of sight, and nothing else comes to be from sight besides this), but from others something comes to be (as a house from the art of building, besides the building activity), nevertheless, no less in the former case is it the end, and in the latter case it is even more the end of the potentiality. For the building activity is in the thing being built, and it comes to be and exists at the same time as the house. Therefore, in all cases where that which comes to be is something other than the use, the actuality is in the thing being made (as the building activity is in the thing being built, and the weaving activity is in the thing being woven, and similarly in the other cases, and in general motion is in the thing being moved); but in all cases where there is no other work besides the actuality, the actuality exists in the subjects themselves (as seeing is in the seeing subject, contemplation is in the contemplating subject, and life is in the soul, and therefore happiness too; for happiness is a certain kind of life). So it is clear that substance and form are actuality. According to this argument, then, it is clear that actuality is prior in substance to potentiality; and, as we have said, in time one actuality always precedes another, right back to the actuality of the eternal first mover. But indeed, actuality is prior also in a more authoritative sense; for eternal things are prior in substance to destructible things, and nothing which is eternal exists potentially. And the argument is as follows: every potentiality is at the same time a potentiality for the contradiction; for that which is not capable of existing could not exist in anything, but everything which is capable may possibly not act. Therefore, that which is capable of being may possibly both be and not be; the same thing, then, is capable both of being and of not being. And that which is capable of not being may possibly not be; and that which may possibly not be is destructible, either absolutely or in respect of this very thing which it is said that it may possibly not be, whether in place or in quantity or quality; and ‘absolutely’ means in respect of substance. Therefore, nothing of things which are absolutely indestructible exists potentially in an absolute sense (though there is nothing to prevent its being so in some respect, for instance in quality or place); therefore all eternal things are in actuality. Nor do any of the things that exist of necessity exist potentially (and yet these are primary; for if these did not exist, nothing would exist). Nor indeed is motion potential, if there is any eternal motion; nor, if there is any eternal moved thing, is it moved in respect of potentiality, except in moving from somewhere to somewhere (and nothing prevents matter existing for this). Therefore the sun and the stars and the whole heaven are always active, and there is no fear that they will ever stop, as the writers on nature fear. Nor do they tire in doing this; for their motion is not concerned with the potentiality for the contradiction, as is the case with destructible things, so that the continuity of the motion should be laborious; for the cause of this laboriousness is that their substance is matter and potentiality, not actuality. And those things which are in change, such as earth and fire, imitate the indestructible things. For these too are always active; for they have motion of themselves and in themselves. But the other potentialities, as we have distinguished them, are all potentialities for the contradiction; for that which is capable of moving in this way is also capable of not moving in this way, at least in the case of those with rational principles; as for the irrational ones, they too will be for the contradiction by their presence and absence. If, then, there are any such natures or substances as those who discuss the Forms speak of, there would be something much more knowing than knowledge itself, and something more moving than motion itself; for the former are more actual, whereas the Forms are potentialities for them. It is clear, then, that actuality is prior both to potentiality and to every principle of change.