It's time to take some of the things we know about light and put them to good use. In this chapter, the author discusses various optical instruments like antennae and lenses, and in the Applications section, you get to learn how telescopes work. That's just too darned exciting, isn't it? In case you're wondering what the heck this chapter title refers to, it's a phrase theater directors are often hear saying, and you'll understand what it has to do with the material in the chapter once you've read it.