Sigmund Freud

Freud proposed that the human psyche was not one entity, but actually composed of three separate aspects. These are called the Id, Ego and Superego. He developed the theory that humans have an unconscious in which sexual and aggressive impulses are in perpetual conflict for supremacy with the defences against them. In 1897, he began an intensive analysis of himself. In 1900, his major work 'The Interpretation of Dreams' was published in which Freud analysed dreams in terms of unconscious desires and experiences.
-The ID is the part of us that has the most primal instincts, such as aggression and sexual desires. This version of us does not conform to today's societal norms, and is the most representative of our original ancestors, as these traits were needed for humans to desire, but we have not and will not completely subside completely. These characteristics are often controlled but some times they become our primary intentions.

-The Superego is the part of us that has been shaped and moulded by societal norms and conventions. This part of us is created with a strive for perfection and takes in to account how our regulated society wants us to be. This model acts solely on what is 'morally correct' and is in a constant conflict with the Id to control us.
-The Ego is in the middle of the Id and Superego and can be thought of as the conclusion that we come to when considering both the desires of the Ego and Id. It is the middle ground between the two and often compromises between them to satisfy the needs of both. As it is, the Ego is the version of ourselves that we project most often to the outside world, as the other two are too extreme versions of ourselves for us to be seen as a normal person.