I imagine the spiral symbolizes the point past which a person becomes proficient enough to write Elisp easily. The person then realizes the infinite malleability of Emacs and begins customizing it endlessly.

It looks like Debian's logo: https://www.debian.org/ -- but I'm not sure if it's trying to imply emacs is impossible to learn or something.

Emacs uses lisp and loads of recursive functions. I imagine the spiral has something to do with recursion.