  Personalists insist that in his contact with the world the human person acts not in a purely mechanical or deterministic way, but from the inner self, as a subjective “I,” with the power of self-determination.  Possession of free will means that the human person is his own master (sui iuris). Self-mastery and freedom characterize personal beings; a free being is a person. The person’s power of self-determination explains the non-transferable nature of personality.  His incommunicability does not only refer to the person’s uniqueness and unrepeatability. What is incommunicable or inalienable in a person is intrinsic to that person’s inner self and to the power of self-determination. No one can substitute his act of will for another’s.