In this Episode we're talking with Dick Gabriel on Lisp. We started by looking at artificial intelligence as the historic context of Lisp, the goals AI tried to reach, and how Lisp was supposed to help reach those. We then discussed the language itself, starting with the Data As Program / Program As Data concept that is a foundation for Lisp. Then we discussed adding a meta-circular interpreter, programming as language development, and the blurred boundary between language and frameworks (because everything uses the same syntax). We then talked about Lisp's type system and the importance of macros to extend the language. The next section concerned CLOS, the Common Lisp Object System and its important concepts: generic functions, multimethods, mixins, and method combination. We also briefly looked at the meta-object protocol but agreed this is a topic for a separate episode. After a discussion about the various dialects of Lisp and Scheme, we concluded the Lisp discussion by explaining why Lisp did not really catch on ("AI Winter") and Lisp's role in today's industry. We ended the episode with a couple of details about Dick's other life as a poet and his Poem a Day effort. Make sure you listen till the end, where we have added a song about Lisp (courtesy of Prometheus Music.)