The ego represents what may be called reason and common sense, in contrast to the id, which contains the passions.
Until the boy’s sexual wishes in regard to his mother become more intense and his father is perceived as an obstacle to them; from this the Oedipus complex originates.
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.
Analysis does not set out to make pathological reactions impossible, but to give the patient’s ego freedom to decide one way or the other.