One might compare the relation of the ego to the id with that between a rider and his horse. The horse provides the locomotor energy, and the rider has the prerogative of determining the goal and of guiding the movements of his powerful mount towards it. But all too often in the relations between the ego and the id we find a picture of the less ideal situation in which the rider is obliged to guide his horse in the direction in which it itself wants to go.
Sigmund FreudA transference neurosis corresponds to a conflict between ego and id, a narcissistic neurosis corresponds to that between between ego and super-ego, and a psychosis to that between ego and outer world.
Sigmund FreudThe moment a man questions the meaning and value of life, he is sick, since objectively neither has any existence; by asking this question one is merely admitting to a store of unsatisfied libido to which something else must have happened, a kind of fermentation leading to sadness and depression.
Sigmund Freud