I'm sure you've done the same thing. You're yodelling along with "We Three Kings of Orient Are," enjoying the vivid depictions of the christological significance of each gift, you make your way through the refrain in honor of the star, and then at the very end you choke--you sing "Guide us with thy perfect light" or maybe "Guide us to by thy perfect light" because, after all, that's what the star is there to do, guide those kings along... but that's not what the verse says. In fact it says something far more significant: "Guide us to thy perfect light." The light of the star is not perfect; quite ordinary, in fact, beside the real light to which it leads. Christ himself is the perfect light, the light of the world, the light no darkness can overcome. Light brackets the ordinary green of the ensuing season of Epiphany--first the bright light of the star leading to the brighter light of the Christ child, and later the light brighter than any fuller can bleach radiating from the transfigured Christ. So go on making the mistake when you sing--and enjoy the deeper knowledge that comes as a result of the mistake. Felix culpa indeed!