Godel's Incompleteness Theory states that within an axiomatic system, there are statements that are true that you can't prove true. You can only prove them true if you go up a level.

In programming (assuming a "computer language" as an analog to "axiomatic system"), there are abstractions that cannot be implemented. You can only implement them by going up a level.

In LISP, you have this "going up a level" ability with macros. The only reason this works for LISP is that the language is written in terms of data LISP can manipulate, meaning you can manipulate code at compile time. Forth has an ability to "go up a level" as well, with a defined way to extend the compiler.