Hitchcock once called his movies slices of cake, not of life. The concept of pure cinema conveys the notion that film should not refer to any other art form but itself. A film is not a novel, not a painting, not music, though it contains literary, visual, musical and other elements. The typical method of creating pure cinema is montage through edits and dissolves. Edits shift abruptly from one image to the next to indicate continuity in motion.
Dissolves gradually move one image over another to stretch time and move into another space.
These techniques, not coincidentally, are familiar to everybody who has ever seen a movie but are rarely noticed by anyone. Edit within a scene to indicate continuity. Dissolve from one image to the next to move to another scene. Hitchcock was the master of pure cinema. Time and again, he created suggestions through filmic means alone.