“In the early days of television, when the “kitchen sink” school of realism held sway, we always reached a point where we “explained” the character. Around two-thirds of the way through, someone articulated the psychological truth that made the character the person he was. Chayefsky and I used to call this the “rubber-ducky” school of drama: “Someone once took his rubber ducky away from him, and that’s why he’s a deranged killer.” That was the fashion then, and with many producers and studios it still is.”
— Sidney Lumet, Making Movies