From American Cinematographer, Common Sense and Camera Angles by William Stull, ASC (Feb. 1932)
"After the players are well rehearsed, I study the action through the camera's viewfinder, or through the recorder's earphones... Most frequently, I study it through the camera, for the visual must predominate in a motion picture. It is not only the action that is important, but the way in which the camera sees the action. The cinematographer must light the action to exactly match the mood in which it is played, and must have his camera at exactly the right position matching the dramatic perspective of the scene. This is the salient point about camera angles: They must be used to match the dramatic angle of the scene, [and] never for their own sake... If they aid the dramatic progress of the picture, they are good, and must be used; if they hinder it, they must not... But the use of camera angles extends beyond this. It definitely enters the realm of the psychological. It can convey the underlying significance of a scene as nothing else can."
- Rouben Mamoulian