The Big I is a term used to refer to the EGO, which is the part of the psyche that is responsible for a person's sense of self. It is the part of the mind that is conscious and aware of one's identity, and it is the part of the psyche that is responsible for a person's sense of self-worth and self-esteem. The EGO is often seen as the mediator between the conscious and unconscious mind, and it is the part of the psyche that is responsible for making decisions and forming opinions.