This quote has always seemed very strange to me. I feel like the implicit argument (that just using lisp instead of making a program that has more limited seman

This quote has always seemed very strange to me. I feel like the implicit argument (that just using lisp instead of making a program that has more limited semantics that conform directly to the intended purpose) is not a great one. Obviously informally-specified, bug-ridden, and slow are not good things, but I'd argue those are also not specific to Fortran or C but just to any "sufficiently complicated program". People make a big deal about the Church-Turing thesis, but I think it gets taken too far sometimes because the important part of a programming language isn't always what's possible to do in the language but what _isn't_, and I'd argue most of the large improvements in languages over time are about that; not having undefined behavior, null-pointer errors, and runtime type errors are all huge improvements in programming productivity that only exist because we made languages that don't allow you to do certain things. At the end of the day, quite a lot of the work in programming boils down to ensuring that what you wrote does _exactly_ what you intend rather than behaving in some other way, and that means identifying and eliminating places where it diverges. There are a lot of common patterns for places where these issues occur, and a language that can identify those patterns and make it impossible for you to write a program that has those mistakes is saving you time up front.