What is z?
It is the interface between Acting and Feeling.
As an attribute, it is an attribute of the ego, an extension of the ego, the attribute we call self-acceptance.
Self-acceptance to animals is a non-issue. That is, they can not not be self-accepting. To us humans it is a choice. We can accept ourselves OR reject our-Self OR engage in many of the various degrees inbetween.
Self-acceptance as a capacity is something we should develope in ourselves, which is to say it is a psychological characteristic we should value.
If we do not value self-acceptance we will not be self-accepting. If we are not self-accepting we will not assert that of which we are not accepting. To not assert ourself means to not act. To not act means to not live. To not live means to not value.
Since life is the ultimate value, living and valuing are the same thing and as such you can't have one without the other.
Self-acceptance is the most important of the fundamental psychological values and we should most definitely value it and value it highly.*