The motif of doors

While watching The Godfather, it was noticed that the motifs of doors and camera angles were played with together to create different levels of inclusion of the audience. Some angles like the low one through the doorframe and where the man went outside of camera view are still a mystery to me because I have only seen about a quarter of the movie. Another thing that was noticed is that the good things that happen in the movie happen outside. An example of this is the wedding and we know it is more than a coincidence because it occurs more than once with Kay and Michael Christmas shopping. To contrast this, all the bad things happen indoors like the killing of Luca Brazzi and Mr. Waltz waking up with the horse in his bed. Something intriguing that could be further analyzed is that the scene where Sonny was having sex with Lucy, they were leaning against a doorway and this could be interpreted as being still a good thing, but because they were almost outside of the door, it was almost a bad decision. This was a short scene and because it was random and did not make the plot move forward, it was put in for a reason.