The Aristotelian dictum that desire is the starting point of practical reasoning that ends in action can of course be denied. Its denial is a commonplace of moral theory in the tradition of Kant. But in this essay I am concerned with that issue only indirectly. I shall not contend that rational action always or necessarily does involve desire as its starting point; nor shall I deny it. My question concerns instead the possibility of its ever beginning in desire. For there is a question whether it is even possible for reasoning to begin in desire, a question arising from the nature of desire and its objects, which to my knowledge has not been articulated. If we can see how desire can provide the arche of action, then we can consider later, and from that vantage point, whether it is necessary that it should do so. It will, I think, be possible eventually to argue that if practical reasoning has the character it must have, if it can begin in desire, then its starting point can be nothing but desire.