Hitchcock: Well, the silent pictures were the purest form of cinema; the only thing they lacked was the sound of people talking and the noises. But this slight imperfection did not warrant the major changes that sound brought in. In other words, since all that was missing was simply natural sound, there was no need to go to the other extreme and completely abandon the technique of the pure motion picture, the way they did when sound came in.
Truffaut: I agree. In the final era of silent movies, the great film-makers — in fact, almost the whole of production — had reached something near perfection. The introduction of sound, in a way, jeopardized that perfection. I mean that this was precisely the time when the high screen standards of so many brilliant directors showed up the woeful inadequacy of the others, and the lesser talents were gradually being eliminated from the field. In this sense one might say that mediocrity came back into its own with the advent of sound.