In recent years there has been an explosion of writing on David Hume. His scepticism, his writings on morality, politics, and religion, have all received substantial attention. What I attempt to do in this thesis is to suggest that his revolutionary contributions in all these fields can be better understood if we consider his attempt to found the sciences on the imagination. What little work there is on the imagination in Hume's writings is almost all concerned with Book I of the Treatise. As regards Book I, I suggest that Hume's overarching problem is to argue that belief is dependent on the imagination, whilst still keeping a contrast with the whims of the 'fancy'. He wants to disabuse us of the idea that we believe on account of reason; but he wants to distinguish the claims of science from the claims of poets. But I also examine why he thinks his explanation of the production of passions support his conclusions about belief. And I argue that his former account guides conclusions found in other genres. So for example, I examine certain essays and letters about politics, and his explanation of religious events in the History of England. Why do men falsely believe that they are distinguished from the animals through possessing reason? On the one hand Hume tries to explain the origin of the sciences; on the other hand, he tries to show how men have come to have a false conception of themselves. A central aim of the thesis is to bring out these themes through showing the use Hume makes of principles of the imagination. I pay special attention to Hume's attempt to argue that Christianity plays a major role in the sustaining of the false view.