In case that the power did not exist, also it would not have devir, therefore all the beings would be immovable and perpetual. But the pure act is absolutely perfect, because of the potentiality absence. In the epistemolgico aspect, that is, of the point of view of the knowledge the being in act if overlaps to the being in power, therefore this beyond being determined is not submissa to the being in act, therefore we only know it in virtue of a being in act. Converting these slight knowledge, power and act, in essence and existence, it is understood that the essence alone is understood in virtue of the existence. Second, of the point of view of the causalidade the act is superior again the power, why in the ticket of the power to the act, it requires a being in act.
Therefore, the power does not exist for itself, but in function of the act, therefore in the cycle of the causalidade, all being in power is present in a being in act. In this digresso Aristotle it proves the existence of ' ' Deus' ' , by means of the argument of the immovable engine. Finally, of the point of view of the composition, the act also surpasses the power, therefore it are of the act does not have power, therefore this is not found in pure state in the nature. For the fact of to be something determinable. The act and the power in relation with the substance the relation of the act and the power with the substance is established for Aristotle, leaving of the two constituent elements of the substance, the substance and the form. Abbagnano defines substance as ' ' what it is (…) what necessariamente.' exists; ' (ABBAGNANO, 2007, P. 925) this concept is purely aristotelian. The substance in the aristotelian conception is the power of the substance, while capacity to assume or to receive the form.