Even if you don't understand Lisp (the meaning of various operators), the structure of a Lisp function is already clear. All you have to understand is symbols, spaces, and parentheses; a lot of that comes from Western writing systems already (which use symbols separated by spaces (and parentheses)). The one piece of common knowledge that you dno't get to apply in Lisp is the writing system for infix arithmetic. (It can be easily put in as a small library module, but nobody ever uses it.)