Freudian theory about the structure of the psyche (Id, Ego, and Super ego) show up in film quite often.
An example of this are movies done by the "Marx brothers", where each of the three brothers often represents a part of the psyche.

(On a side note: on stage there were five Marx brothers, but once they stared in movies only three of them became widely popular)
Harpo, representing Id:
Harpo often has clashes with the rest of society. Like the Id, Harpo's unbridled demands often put him at odds with people.
Harpo, like the libido part of Id, chases after whatever he wants. Often, Harpo is chasing women, however, he will drop the chase immediately if something else catches his interest. (Like a harp)
Harpo (Id) often has friendly clashes with Groucho (who represents Ego) when interrupting whatever Groucho is trying to do. Chico, representing the Super-Ego:
Chico is like the Super-ego in that he is always forcing a compromise between Harpo (Id) and Groucho. (Ego) Chico is always the first to recognize that the three brothers should help the romantic couple get over their obstacles.

In some of the movies Chico plays a Super-ego more closely in line with the desires of the Id, (chasing women is what got him named "Chico" in the first place) but even then he always is loyal and does what he knows to be right.

Chico is like the Super-ego in his being the bridge between Harpo (the Id) and Groucho. (Ego) Chico is almost always the companion of Harpo, and acts as his translator.
Groucho, representing Ego:
Groucho, like the Ego, is always scheming to try and get a comfortable life. He is almost always making sarcastic remarks, and smart-mouthing in general.
Groucho is the Marx brother who interacts the most, and the most successfully with the people around him. Groucho is almost always chasing wealth instead of women, this is often the reason he is interested in Margaret Dumont's characters.
Often, Groucho is trying to get the three brothers to follow his plan, he almost always ends up explaining his plan to Chico. Chico often confuses him to the point where his plans don't even make sense to him! (Notice the relationship of the Ego submitting it's ideas to the scrutiny of the Super-ego)
Conclusion:

The three of them always have to work together before the story can end. The three brothers represent a complete, though incredibly wacky character.
*The source for all the pictures in this blog posting is the movie "Duck Soup" I used Jing (A TechSmith product) to capture these images from my copy of the movie.
















