I think I meant what I said :-), which is that closing over a lexical variable in Lisp, using LET, more clearly, to my eyes at least, show which variables are hidden/closed over.

For example, in CL, this guy's example would take the general form:

(let ((counter 0))

   (defun tally () 

      (incf counter)))

So, in this form, I know that TALLY hides/closes over COUNTER, without needing to inspect the function body (either before, or within a λ that might be returned from within the function body).