Sigmund freud once said that the id was like a wild horse and that the "ego" was like a rider astride the horse, struggling to keep it under control.
As per Freud's model of the psyche, the id is the crude and instinctual part of the mind that contains sexual and forceful drives and concealed recollections, the super-ego works as an ethical still, small voice, and the ego is the reasonable part that intercedes between the wants of the id and the super-ego.