I studied philosophy and theology at Boston University under Edgar S. Brightman and L. Harold DeWolf. I did most of my work under Dr. DeWolf, who is a very dear friend of mine, and, of course, I was greatly influenced by him and by Dr. Brightman, whom I had the privilege to study with before he passed on. It was mainly under these teachers that I studied Personalistic philosophy--the theory that the clue to the meaning of ultimate reality is found in personality. This personal idealism remains today my basic philosophical position. Personalism's insistence that only personality-finite and infinite-is ultimately real strengthened me in two convictions: it gave me metaphysical and philosophical grounding for the idea of a personal God, and it gave me a metaphysical basis for the dignity and worth of all human personality.
Martin Luther King, Jr., The Autobiography of Martin Luther King, Jr., Chapter 4. The reference is to what is known as "Boston Personalism," which is associated with Borden Parker Bowne (Brightman's own teacher). As King notes, Boston Personalism is a form of idealism, holding that everything that exists is either a person or an experience of a person; or, to put it in other words, that reality is constituted by persons, their mental life, and their interactions with each other.