For Hume, understanding the workings of the mind is the key to understanding everything else. There is a sense, therefore, in which to write about Hume's philosophy of mind is to write about all of his philosophy. With that said, I shall nonetheless focus here on those specific doctrines that belong to what we today call the philosophy of mind, given our somewhat narrower conception of it. It should also be remembered that Hume describes his inquiry into the nature and workings of the mind as a science. This is an important clue to understanding both the goals and the results of that inquiry, as well as the methods Hume uses in pursuing it. As we will see, there is a thread running from Hume's project of founding a science of the mind to that of the so-called cognitive sciences of the late twentieth century. For both, the study of the mind is, in important respects, just like the study of any other natural phenomenon. While it would be an overstatement to say that Hume's entire interest lies in the construction of a science in this sense - he has other, more traditionally “philosophical” concerns, as well - a recognition of the centrality of this scientific conception of his subject is essential for understanding him.