The Ego serves three severe masters: the external world, the Super-Ego and the Id.
The Ego comprises the organized part of the personality structure that includes defensive, perceptual, cognitive, and executive functions. These functions include judgment, tolerance, reality testing, control, planning, defense, synthesis, and memory. They all help us to organize our thoughts; and make sense of our inner world and the world around us.
What a gracious act of psychic funambulism must the Ego perform, to accomplish the simple task of keeping us sane.