A consequence of our definition of the proper object of human knowledge -- the abstracted quiddity of the sensible as represented in the phantasy – is that the human intellect cannot obtain direct knowledge of material things. Direct knowledge is opposed to reflex knowledge, which is a way of knowing that requires the intellect to turn back upon either itself, meaning its own act, or upon another cognitive act.
The argument for this consequence is as follows:
1. The proper object of the human intellect is the abstracted quiddity of the sensible as represented in the phantasy.
2. The abstracted quiddity is a universal.
3. Therefore the proper object of the human intellect is the universal.
The thrust of the argument is that something is known by the intellect only inasmuch as it is intelligible, and that a material object can only be rendered intelligible by abstracting it from the very conditions which make it a material object.