I love the story where the creators defined a Lisp interpreter in Lisp, and then one said, "you know, we don't have a Lisp compiler, but I could compile this source by hand." It's quite an elegant concept when you accidentally create a fully-functional interpreter overnight.
> Steve Russell said, look, why don't I program this eval..., and I said to him, ho, ho, you're confusing theory with practice, this eval is intended for reading, not for computing. But he went ahead and did it. That is, he compiled the eval in my paper into IBM 704 machine code, fixing bug, and then advertised this as a Lisp interpreter, which it certainly was. So at that point Lisp had essentially the form that it has today...
a shorter version from "History of Lisp" page 9:
> S.R. Russell noticed that eval could serve as an interpreter for LISP, promptly hand coded it, and we now had a programming language with an interpreter.
