Here Freud reworks his picture of the mind into the three parts that became famous: the id, the ego and the super-ego. The id holds raw drives, the ego tries to deal with reality, and the super-ego carries conscience and ideals. He explores how these parts conflict, how guilt arises, and how the ego must serve several demanding masters. Compact and technical in places, the book is the foundation of what is often called his structural theory of the mind.
Quotes
It is easy to see that the ego is that part of the id which has been modified by the direct influence of the external world.
The ego represents what we call reason and sanity, in contrast to the id which contains the passions.
until the sexual wishes in regard to the mother become more intense and the father is perceived as an obstacle to them; this gives rise to the Oedipus complex.