In a place of deficiency, there is a grip to the Sitra Achra [other side]. Hence, when criticizing, a person is deficient, and then there is a grip to the Sitra Achra. At that time, although one does not feel it, he is nonetheless separated.
But on the right line, when one is in a state of wholeness, there is no grip to the Sitra Achra. At that time, a person is in Kedusha [holiness]. Although it is a small degree, it is nonetheless Kedusha. But on the left line he is deficient and separated.