We understand the Aristotle’s energia or entelikia (in English, ‘act’) first through motion. This means we understand what is actual through what is least actual. Similarly, we are prone to imagine what is most actual (operation) in terms of what is least actual (motion). There are certainly motions of things in the brain and in the eyes which are required for sense knowledge, but the activity of sensing is not a motion. The action of moving is not complete while happening, but the action of sensing or knowing is complete while happening. Heraclitus’s fragment is well applied to the activity of operation: ”moving, it rests”.
(The experience of pleasure is also of operation, and vividly shows the reality of “moving, it rests”.)
The question of whether being is dynamic or static usually ignores the significance of Aristotle calling being an act. Being in one sense divides into substance and accident, but in another sense into act and potency, and at the summit of actuality is operation, which is the fulfillment and perfection of mere existence. When we consider the degrees of actuality, for example, it is better to say that God is an operation than to say he is a substance (to say this, of course, has the defect of not signifying his existence.)