I "got it" after reading a bulk of SICP and watching some buddy-lectures at http://academicearth.org/courses/the-structure-and-interpret... (I've also started SICM: it's awesome how they use Scheme.[1]) Nevertheless there's still a level I have yet to reach that I hope to achieve with Clojure (which has recently jumped to the top of my list of languages to learn). While Lisp (Scheme in particular, though CL is nice too) is near my heart, my brain still thinks in Python, Python makes me Happy, and that hinders my speed and concentration when I do stuff in Lisp. I liken it to my experience trying to (unsuccessfully) master Dvorak. The layout was easy to memorize so I could touch-type, I could easily see the benefits, and if I ever get spasms in my hands I'm going to force myself to switch over, but dropping from 80-100wpm down to 10-30wpm was too much loss that I didn't let my finger-muscles relearn and so I'm still with QWERTY.

[1] Even though it's trivial I still adore this simple example:

    guile> (define D derivative)
    guile> (define f (literal-function 'f))
    guile> (define f^2 (expt f 2))
    guile> (pe ((D f^2) 't))
    (* 2 (f t) ((D f) t))

Add in the little things like being able to have boolean-returning-functions ending with '?', Lisp is very free.