Identification
Identification with mental representations, or a psychic structure
patterned by such representations, is the most fundamental cause
of narcissistic disturbance. (The Point of Existence, pg 91)

One thing that can help our investigation is to connect the feeling
of "I," the feeling of self, to what is called "identity"
or "identification". Finding out who you are is essentially
finding your identity. You can see the connection between identity
and identification, if you look at your experience of any moment,
and see that at that very moment you are identifying with something,
you're taking yourself to be something in particular. You might
not be consciously aware of what you are taking yourself to be,
but at any moment you are taking yourself to be something, or
someone. So what we want to investigate is what or who you are
taking yourself to be at each moment and question it. (Diamond
Heart Book 3, pg 19)

Identification and defense
Our understanding is that to continue identifying with the particular
ego structure is to continue the defense. In all the cases of
an individual going from an ego state to a Being state, the main
defensive maneuver is the identification with an ego structure,
a self-image or an object relation. While it is true that one
must deal with other defense mechanisms, like repression, reaction
formation, projection and so on, ultimately one comes to face
the identification systems themselves as the ultimate and most
subtle defense. (The Pearl Beyond Price, pg 137)

Mind, life and identification
The moment you take yourself to be anything in your mind, you
are split from who you are, and you will experience insecurity,
fear, and desire. The separation from your real self will bring
wants and needs, the thoughts that accompany them, the feelings
that accompany those, and the rest of the mess that most people
call their lives. (Diamond Heart Book 3, pg 91)

Identification systems and the body
The permanent presence of identification systems in the mind
can now be seen as a kind of indigestion or constipation. Any
such system is a mental contraction, which is accompanied by physical
contractions in the body. When inner sensitivity is refined, the
tensions in the body which accompany the identification can be
seen. These tensions are what William Reich called "the body
armor" ...identifying these tension patterns can be very
useful in the process of becoming aware of one's identifications.
(The Pearl Beyond Price, pg 164)