It is important for individual therapists to have what is known as a Theoretical Orientation. This is the therapists understanding of how human pathology develops and the most effective ways of treating it. For Brett, his theoretical orientation is from an experiential psychology perspective.  This includes humanistic psychology elements from the school of Carl Rogers as well as existential psychology particularly Irvin Yalom. For Michael, this understanding is rooted in the work of Anna Freud and her ego psychology as well as her contemporaries in psychodynamic theory. Most specifically Michael subscribes to the self-psychology model promoted by Heintz Kohut. 

Existential Psychology:

 https://www.psychologytoday.com/us/blog/evil-deeds/201101/what-is-existential-psychotherapy \

Self Psychology:

https://www.goodtherapy.org/learn-about-therapy/types/self-psychology