In the mid-80s, while reading through my roommate's collection of Scientific American back issues, I encountered this introduction to Lisp written by Douglas Hofstadter. I found it very charming at the time, and provide it here (somewhat illegally) for the edification of a new generation of Lispers.
In a testament to the timelessness of Lisp, you can still run all the examples below in emacs if you install these aliases:
(defalias 'plus #'+)
(defalias 'quotient #'/)
(defalias 'times #'*)
(defalias 'difference #'-)