The development of this concept is often credited to Don Sahlin, chief architect responsible in many ways for the basic look of the Muppets. Jim Henson explained the importance of eye placement: "It would be the last thing [Sahlin] would do, and he always wanted me there, to make sure it was right for both of us -- making sure the eyes had a point of focus, because without that you had no character." Because the eyes are such an essential element to the mechanics of the characters, Muppet builders usually wait until the last minute to add the eyes.