He actually means just notes; it's not a modest title for a whole book. Most of the ideas apply to all languages. Rule 5 -- data structures over code structures -- is particularly useful. If you look for what makes Unix good, you keep finding Pike's tracks. He co-invented [http://www.cs.bell-labs.com/plan9dist/|Plan9] (a sort of meta-Unix) and [http://www.cl.cam.ac.uk/~mgk25/ucs/utf-8-history.txt|UTF-8] (the least bad character encoding).