
I took Anthony Perkins into my dressing room - he was supposed to be my young lover - and I said, “For heavens sake kiss me!” Anthony did a double-take, then he laughed and said, “Why? What for?” I said, “Because we’ve got to do it later in the film, and I don’t know you, I’m hardly acquainted with you, and I’m shy and I blush. Much better we do our first rehearsal in my dressing room, so that I shan’t start dreading the moment when we have to do it in front of a hundred technicians.” He grinned, and understood, and said, “Okay,” then he kissed me. ― Ingrid Bergman: My Story

A kiss is a lovely trick designed by nature to stop speech when words become superfluous.
I conceived that scene in terms of the participants’ desire not to interrupt the romantic moment. It was essential not to break up the mood, the dramatic atmosphere. Had they broken apart, all the emotion would have been dissipated. And, of course, they had to be in action; they had to go over to the phone that was ringing and keep on embracing throughout the whole call, and I also felt that the public, represented by the camera, was the third party to this embrace. The public was being given the great privilege of embracing Cary Grant and Ingrid Bergman together. It was a kind of temporary ménage à trois. – Alfred Hitchcock