Step by step, I keep getting more and more of what's lisp about.
Not just the syntax (huh?) or the core lib, but idioms, design decisions, and the vision.
One of the mottos of Lisp is the famous 'code is data, and data is code'.
For me, that's not 100% clear yet, but I get more insights every day.
One implication of this is when you look at s-exps and see them as a datastructure, not as code. That's the macro point of view. If you want to know more about macros, I can only recommend you Paul Graham's OnLisp, and Doug Hoyte's Let Over Lambda. I'm now reading through the latter and I find it a perfect companion for OnLisp.
The other direction is 'data is code'. To exemplify this side, here are a couple of links that really get to the point of this (at least one part of the point).
- http://irreal.org/blog/?p=398 <= One of a series of posts comparing xml to sexps. Quite long and insightful
- http://shinkirou.org/blog/2010/06/s-expressions-the-fat-free-alternative-to-json/ => xml->json->sexps.