Every corporeal being is bound to classify the world into two extremely basic categories:
That which can be grabbed (or grabbed by)
That which cannot be reached.
More generally, for each sense, we classify the world into
That which is immediately available to that sense.
That which needs to be indexed into, in order to be available for that sense.
Indexing can take various forms, from body-muscle preparedness to eye-saccades to visual navigation. For every sense, we can make the following classification:
An ‘’actual’’ object (or object part) of that sense into which we have indexed, and which is available for further elaboration or manipulation. For example, having indexed into Leonardo’s Mona Lisa, we can move closer to discern whether Mona Lisa is smiling or not.
A ‘’potential’’ object (or object part) of that sense that will be made available to us with an appropriate amount of effort on our part.
Note that these are phenomenological distinctions; I am not talking about subconscious or unconscious representations in V1 or some other brain area. In our experience of the world, there is a basic division between those things that are immediately available using vision, hearing, touch etc and those that require effort. What is available transparently to one sense might require effort from another — consider the shape of a soccer ball from vision and touch. In any case, the sensory world can be divided into those entities with whom we are in direct contact, and those with whom contact requires effort. We can think of the spatial world in terms of a figure-ground analogy: one the one hand, as Kant pointed out, space is a basic category, it is presupposed in our understanding of anything else. On the other hand, we process detailed spatial information (where objects are, how to catch this baseball etc). The first can be seen as the structuring aspect of space, while the second as consisting of detailed perceptual or encyclopedic information.
We can call this the pointing body versus the pushing body. The pointing body allows us to index into locations (there), objects (that!) and so on. The pushing body helps us interact with those entities that we have pointed to, but these seem to be two very distinct modes of bodily being.