 In his commentary on the Metaphysics, Alexander interprets these arguments as showing that pure knowledge is superior to action. But there is a difference between the claim that there is a kind of knowledge which is an end in itself and the claim that pure knowledge is superior to action. The latter idea is a distinct development in thinking about the relation between knowledge and craft. This development rests on the notion that action implies need and it is better to be without need. So knowledge that fills no need is superior to action, which fills some need or other. We see this idea at work in the auxiliary arguments which Alexander offers to back up or explicate claims made in Aristotle’s text. For instance, when Alexander first claims that Aristotle means to show that knowledge is more honorable than action, he says that action aims at some end other than itself. As though remembering that virtuous action — unlike productive action — has no end outside itself, he immediately offers an argument to the effect that even virtuous actions have reference to the passions. Divine beings, who are without passions, have no need of virtue. Those who have passions need the virtues in order to control the passions (In Metaph. 2, 1–10). Obviously, to have passions is to be in need. The contrast between the divine and the human also figures in another auxiliary argument. In passing, Aristotle says that one might justifiably think that wisdom is beyond human ability because in many ways human nature is in slavery (Metaphysics 982b30). Alexander explicates the remark about slavery by saying that humans are slaves in that they need such things as health and prosperity. But what is divine is free of all need (In Metaph. 17, 15–20).