Sheldon Kopp

Sheldon Kopp (29 March 1929 – 29 March 1999) was a psychotherapist and author, based in Washington, D.C.. He was born in New York City, and received his PhD from the New School for Social Research. In addition to his private practice, he served as a Psychotherapy Supervisor for the Pastoral Counselling and Consultation Centres in Washington. He died of cardiac arrhythmia and pneumonia.
He is also popular for his quotes.
One of them is, "All of the significant battles are waged within the self."