It is unecessary to attempt to understand what this film is about, i also think that it isnt completely necessary to use it as entertainment. Films made during the surrealist movement should be regarded as works of art and UN CHIEN ANDALOU is a work of pure unique genius on Bunuels part. Surrealism often represents the dream world and dreams very rarely make any sense or have any sort of linear narrative in real life. What they often do have is semiology. Many of the symbols in this film could be to do with sexual tension, such as the ants crawling out of the hand and the spacial discontinuity represents the dreamworld, ever had a dream when you are in a room which doesnt look anything like the room you are meant to be in but you know somehow that it just is? These ideas are all interpreted in this film.
It is my feeling that some of the best art ever made is that which was made during the surrealist movement as it allows you to interpret your own readings. UN CHIEN ANDALOU is a classic example of this.