Where does one — who has no knowledge of these prerequisites or about LISP (except that the latter has been heard in programming circles as something esoteric, extremely powerful, etc.) — start, before reading this book?
Another source of awe is about Lisp being more of a programming system than a language, and Common Lisp was the standardization of a lot of efforts towards that by companies making large and industrial pieces of software like operating systems, word processors, and 3D graphics editors. At the language level, "compile", "compile-file", "disassemble", "trace", "break", "step" are all functions or macros available at runtime. When errors happen, if there's not an explicit handler for it (like an exception handler) then the default behavior isn't to crash but to trigger the built-in debugger. And the stack isn't unwound yet, you can inspect the local variables at every layer. (There's very good introspection in general for everything.) Various restarts will be offered at different parts of the stack -- for example, a value was unknown, so enter it now and continue. Or you can recompile your erroneous function and restart execution at one of the stack frames with the original arguments to try again. Or you can apt-get install some foreign dependency and try reloading it without having to redo any of the effort the program had already made along the way.
Again, all part of the language at runtime, not a suite of separate tools. Implementations may offer things beyond this too, like SBCL's code coverage or profiling features. All the features of the language are designed with this interactivity and redefinability in mind though -- if you redefine a class definition, existing objects will be updated, but you can control that more finely if you need to by first making a new update-instance-for-redefined-class method. (Methods aren't owned by classes, unlike other OOP languages, which I think eliminates a lot of the OOP design problems associated with those other languages.)
I like the book Successful Lisp as a tour of Common Lisp, it's got a suggested reading order in ch 2 for different skill levels: https://dept-info.labri.fr/~strandh/Teaching/MTP/Common/Davi... It's dated in parts as far as tooling goes but if you're mostly interested in reading about some bits rather than actively getting into programming with Lisp that's not so bad. If you do want to get into it, https://lispcookbook.github.io/cl-cookbook/ has some resources on getting started with a Lisp implementation and text editor (doesn't have to be emacs).