By contrast, the forces of opacity (ovyut) and hardness (kashyut) in the partition are regarded as impacting against the surrounding light, which wants to be enclothed within the partzuf, and prevent it from being enclothed in the same way that the partition impacts on the supernal light at the moment of the fusion through collision. These impacts that the surrounding light and the opacity of the partition strike against one another are called the beating of the surrounding light on the inner light.
However, this beating is carried out between them only in the body of the partzuf, since it is only there that the enclothing of the light in the vessels, which leaves the surrounding light outside the vessel, is discernible. This is not the case for the ten sefirot of the head. This beating does not occur there, since there the returning light is not categorized as true vessels at all, but only as thin roots, that is, as potential for forming vessels.
Consequently, the light within the vessels of the head is not categorized as circumscribed inner light to the extent that the light remaining outside can comparatively be regarded as surrounding light.50As explained in the note to section #33# above, the head of the partzuf can be thought of as referring to the theoretical potential of the process of forming proper receiving vessels, while the body of the partzuf is the actualization of the process.
It is only in its full form, where it contains both body and head, that the amount of supernal light received in the body vessel structure can be called inner light and the rest of the supernal light that remains outside the partzuf can be called the surrounding light.