Question About Freud Line

I've remembered one line since I saw this movie when it came out and have wondered about since. When the romantic leads start kissing, Freud turns to the camera and says, "Love is nature's way of reminding men, when they think they are rational gods, of the animals they still are."

I'm not sure if that's the exact wording but I'd like to know if the idea is Freud's or the screenwriter's. It's the most memorable part of the whole movie.