My Lisp Experiences and the Development of GNU Emacs (2002)
The principle of writing a fast core in C, and choosing a Turing-complete language as the language to build the tool, and further giving the user an interpreter so that (s)he can extend it, is a brilliant design. Whether or not you are a Lisp fan or an Emacs user, this is a great way to build a sophisticated tool.<p>While the unix tool philosophy is to do one thing and do it well, Emacs shows that it is possible to build software which lasts 50 years by going the other way as well, as long as there is a philosophy of empowering the user.