One by one the three upper parts of the quartet (the cello, necessarily, remains seated) rise and turn their backs to the audience and each other. At first this looks like a cheap gesture, a gimmick for the end of the work. Each player only has two remember a couple of notes after all, and none of them need to see each other at this stage; if it's too easy, it's not theatre.
Theatrical effects have to be perceived as difficult, otherwise they are merely cheap gimmicks. Harry Houdini, the famous magician/escape artist, certainly knew that he had to make the escapes look hard to get the audience excited. When he was starting out, he would get out of handcuffs and straightjackets in seconds, showing how easy it was for him. The audiences booed, figuring it was just a cheap trick if he could do it so easily. I think Tim is applying this rule to theatrical effects. If the effect is too easy, the audience won't really notice it or figure out what the purpose is. But when it is obviously difficult, as when the quartet restarts in sync while blind to each other, the audience gasps at the impossibility, opening them up for other insights and inspirations. I had never thought about stage effects that way before, it is quite interesting.
Tim's other post is from his series on Music Since 1960. The most recent entry is on Morton Feldman's Rothko Chapel. Tim intersperses diary-like real-time observations with interpretations of how the effects were made or why the effects are so magical or meaningful. The diary observations are magical themselves, drawing the reader into Tim's world of Feldman music: A great swell from choir and timpani. At its climax is an impassioned viola flourish, augmented by tubular bells. A sound of grief, of pain. And again. Was that really pain, then? Can I believe what I felt when I heard it?
I am not familiar with this particular piece. It has inspired me to check the university library, to make sure that we have recordings of all the pieces on Tim's list and on Steve Hicken's list. This is both for my benefit and for the benefit of my students. Tim and Steve have each provided a great resource for the discussion of 20th century music, and I would be remiss if I didn't utilize them.