or properties that determine its existence apart from human perception of it, such as its mass or texture. The apple itself is also “pure substance in which is supposed to provide some sort of ‘unknown support’ to the observable qualities of things” that the human mind perceives. The foundational or support qualities are called primary essences which “in the case of physical substances, are the underlying physical causes of the object's observable qualities”. But then what is an object except “the owner or support of other properties”? Locke rejects Aristotle's category of the forms, and develops mixed ideas about what substance or “first essence” means. Locke's solution to confusion about first essence is to argue that objects simply are what they are – made up of microscopic particles existing because they exist. According to Locke, the mind cannot completely grasp the idea of a substance as it “always falls beyond knowledge”. There is a gap between what first essence truly means and the mind's perception of it that Locke believes the mind cannot bridge, objects in their primary qualities must exist apart from human perception. The molecular combination of atoms in first essence then forms the solid base that humans can perceive and add qualities to describe - the only way humans can possibly begin to perceive an object. The way to perceive the qualities of an apple is from the combination of the primary qualities to form the secondary qualities. These qualities are then used to group the substances into different categories that “depend on the properties [humans] happen to be able to perceive”. The taste of an apple or the feeling of its smoothness are not traits inherent to the fruit but are the power of the primary qualities to produce an idea about that object in the mind. The reason that humans can't sense the actual primary qualities is the mental distance from the object; thus, Locke argues, objects remain nominal for humans. Therefore, the argument then returns to how “a philosopher has no other idea of those substances than what is framed by a collection of those simple ideas which are found in them.” The mind's conception of substances “[is] complex rather than simple” and “has no (supposedly innate) clear and distinct idea of matter that can be revealed through intellectual abstraction away from sensory qualities”. The last quality of substance is the way the perceived