3 - Diagonal Polarities and the Bodyself
The differentiation that occurs here is of the diagonal polarities i.e. form and emptiness (and emptiness and form).
This is customarily referred to - in psychological terms - as the differentiation of the bodyself.
Quite literally - through identification with this primitive body - the baby infant is now able to discriminate an existence (as form) that is distinct from nothing (as emptiness).
However considerable confusion still remains with respect to both vertical and horizontal polarities.
In other words the infant is not yet able to properly distinguish an individual self-identity from the collective identity of the mother i.e. representing the confusion of whole and part.
Even less is the infant able to clearly distinguish an interior sense of self from exterior manifested phenomena (as objects).