I got my copy back in the (gasp) '80s from the neighborhood B. Dalton's or something, and it totally changed the way I thought about the roles of code and data. It's one of the handful of books that have survived all my library downsizing, along with The Tao of Programming, the bible, the dragon book...
I might be buying the book if I really like it to support the authors, but it’s great that they made it available for everyone.