I examine the relation between the action of producing a change (kinêsis) in something else and the action of exercising one’s nature or craft (energeia). I call for the distinction between kinêsis and energeia by arguing that in Metaphysics IX.1-5 change should be construed as a transformational change that is still characterized in accordance with the categories, whereas in Met. IX.6-9 the action of exercising of one’s nature or craft should be construed as the presence of a state or an action that exhibits one’s nature or craft, which is meant to be a way of characterizing that-which-is (to on) that goes beyond the categories. Instead of the conventional patient-centered account of change, I argue that Phys. III.3 and V.4 suggest a non-patient-centered account of change and that the agent’s acting-upon (poiêsis) should also be construed as a non-self-contained change, just as the patient’s being-acted-upon (pathêsis), and therefore cannot be conflated with exercising one’s nature or craft. I also point out that a genuine Aristotelian event cannot be composed of the agent’s acting-upon and the patient’s being-acted-upon. I argue that Phys. VII.3 suggests a two-way relation between the action of producing a change in something else and the action of exhibiting one’s own nature, based on which I outline a hylomorphic proposal that a genuine Aristotelian event is composed of the action of producing a change in something else as the material part of the event and the action of exhibiting one’s own nature as the formal part of the event. While the former provides the material necessitation force from the bottom up to the occurrence of the event, the latter provides the formal constraint force from the top down to the occurrence of the event. / text