Fernandez and Mittelmann focus on Aristotle’s analogy between the soul as an efficient cause and a craft. They argue that the acts of a craft are a special kind of vital act of a rational soul and that the continuous unifying activity of the source of motion in those cases, which must be constantly and not episodically at work in and throughout each of its acts, is not an idiosyncratic feature of the rational case, but the rational version of a form of efficient causality that is at work in all those vital phenomena of which the soul is said to be the efficient cause.