RMS relates how programming Multics Emacs was so convenient that secretaries started to learn to use it:
… The language that you build your extensions on shouldn't be thought of as a programming language in afterthought; it should be designed as a programming language. In fact, we discovered that the best programming language for that purpose was Lisp.
It was Bernie Greenberg, who discovered that it was (5). He wrote a version of Emacs in Multics MacLisp, and he wrote his commands in MacLisp in a straightforward fashion. The editor itself was written entirely in Lisp. Multics Emacs proved to be a great success — programming new editing commands was so convenient that even the secretaries in his office started learning how to use it. They used a manual someone had written which showed how to extend Emacs, but didn't say it was a programming. So the secretaries, who believed they couldn't do programming, weren't scared off. They read the manual, discovered they could do useful things and they learned to program.
So Bernie saw that an application — a program that does something useful for you — which has Lisp inside it and which you could extend by rewriting the Lisp programs, is actually a very good way for people to learn programming. It gives them a chance to write small programs that are useful for them, which in most arenas you can't possibly do. They can get encouragement for their own practical use — at the stage where it's the hardest — where they don't believe they can program, until they get to the point where they are programmers.