The title is a “controversial” quote from the book Hackers and Painters. The book’s author calls it controversial; I call it blindingly obvious but still not seen by certain people.
That book serves as an example that, even though programming languages differ, not everyone agrees on the “important” criteria. In his world, Lisp is the best language, so his criteria match that (e.g. recursion, dynamic typing, garbage collection). Lisp’s ability to write a program that creates a program (see “macros”) gets his highest praise, something much more powerful than c’s #define macros. [For my take on the matter, look at my scorn of #defines, below, then imagine making it even more powerful].
Another thing [that I may just be imagining] I noticed was a hint of sour grapes. Specifically, I’m guessing when Yahoo bought his company and its Lisp code, Yahoo immediately began re-writing the system in a language that emphasized other criteria over “power”, for example, “maintainability”, or “readability”.
Finally, his catch phrase “Lisp has no syntax” is just hilarious. It serves as the definitive example of why the book is kind of a test: Can you spot the falsehoods? The book is thought-provoking, sure, but falsehoods abound nonetheless, sometimes in a Jabberwocky “words mean what I choose them to mean” way. My reference on macros, above, must drive him nuts since the first line is “Macros in Lisp provide a very powerful and flexible method of extending Lisp syntax”.