The fourth season of The Twilight Zone aired Thursdays at 9:00–10:00 pm on CBS from January 3 to May 23, 1963.
The opening sequence was revamped, and introduces the now-iconic floating door, smashed window, clock, eyeball, wooden doll, and the equation for Einstein's theory of relativity.
Rod Serling's introduction was also changed from the earlier seasons: "You unlock this door with the key of imagination.
You're moving into a land of both shadow and substance, of things and ideas.
"[1] An intermission graphic based on this opening was used for the fourth and fifth seasons as well.