David Hume’s project in A Treatise of Human Nature is founded upon his loosely-defined distinction between impressions and ideas. This distinction causes problems for his theory because it has difficulty accounting for the differences between species of perceptions. In this thesis, I try to solve some of these issues using a phenomenological account of the difference between impressions and ideas. My account supplements Stephen Everson’s “functional” account to create a more robust system for differentiating Hume’s perceptions.