Sidebar in an imaginary high school textbook on imaginary numbers:

What is i?

I don’t want to get into this horrible, difficult question right now. One time I was teaching a group of precocious young fiends who asked me this question over and over until I had to hide under my desk. There they surrounded me, and all I could do was plead with them that i was that peculiar thing that multiplies and adds just like other numbers (associatively, commutatively, and distributively), but when you square it the answer is -1. But they all just shrieked back at me, “That doesn’t tell us what i is at all!”—except for one little monster who just kept screaming, “Why?” Just when I had decided to dash my brains out against the underside of the desk, the principal of the school walked in and swiftly settled the matter. “Look,” he said, casting an authoritative glance about the room, “Mr. Smith’s answer may not have addressed your question, but it has told you all you need to know in order to get the right answers on the Exam, and that is all Mr. Smith is here for—to tell you how to get the right answers on the Exam. Any questions that do not pertain to getting the right answers on the Exam, you can ask me in my office, after school hours. But you will please not bother Mr. Smith anymore with it.” He then lifted me from under the desk, installed me back at the podium, whispered something encouraging in my ear, and left the classroom. I felt a bit shaky through the rest of the period, but at least the kids had shut up. —As should you.