 This alternate scheme (Primary and Non-Primary), although partitioning ideas differently than the initial scheme (Innate, Adventitious, and Factitious), appears to do no philosophical harm to Descartes’ view. Even so, it is interesting the extent to which Descartes’ category of primary idea is later echoed in the views of John Locke and David Hume, whose respective theories require a similar category, which they refer to as simple idea. 