Hume’s thesis that reason alone does not motivate is taken as the ground for this theory: Reason produces beliefs only, and beliefs are mere representations of fact, which, without passions for the objects the beliefs concern, cannot move anyone at all. Discussions of the Humean theory of motivation usually begin with the motivating passions in place without asking about their genesis. This emphasis, I think, overlooks a good deal of what Hume’s thesis concerning the motivational impotence of reason is about: It concerns the incapacity of reason to generate the motivating passions in the first place, and not just the ineffectiveness of beliefs, without passions, to produce action. [...] In this paper, I will offer an interpretation of Hume's theory of motive formation and show how it provides crucial support for a famous claim in his argument against the moral rationalists[...]. As it turns out, reason does play a necessary role in motive formation even for Hume, but the answer why it is not sufficient is a telling difference between a rationalist moral psychology and Hume's.