In his Essay, John Locke proposes that what makes something a "body' is its possession of primary qualities. What Locke describes in this context as a "body we might prefer to describe as a "material object'. In Locke's sense of "body', mountains and suitcases are bodies; sounds, holograms and shadows are not. The qualities which Locke identifies as primary are solidity, extension, figure, motion or rest, and number. Of these, solidity is said to be the most important or fundamental primary quality, the one that is "most intimately connected with and essential to Body' (1975: 123).