Stumbled across this today. I somehow followed the rabbit hole from Hacker News or maybe it was linked from there directly:
Source page here.
I'm a working Common Lisp programmer. I have just GOT to be the stupidest Common Lisp programmer alive, so let me tell you how I learnt Common Lisp.
1. Buy ANSI Common Lisp by Paul Graham.
2. Read it. But if you feel your balls retract and your head starts spinning, just stop. Read David Tourestky's (sp?) Gentle Introduction to Symbolic Computation with Common Lisp. (or something like that - it's free and on the web). Go back to Paul Graham. It will be MUCH easier.
3. Next read Object oriented programming with common lisp by Sonya Keene. This is the best tutorial on object oriented programming ever.
4. Next read Paradigms of Artificial Intelligence Programming with Common Lisp for experience on writing real world common lisp.
When learning CL use a trial edition of a commercial environmentment: www.franz.com www.lispworks.com
Ignore ANYONE that recommends learning scheme or reading books teach scheme (i.e. structured interpretation of computer programs or simply scheme blah blah total waste of time (okay except for How to Design Programs - that wasn't half bad)).