Rick wrote jfli, a Java foreign language interface for Common Lisp, before working on Clojure. He was a seasoned lisper, and he wanted to do something both modern and practical.
It's very interesting to go through the bookshelf he read during his sabatical. He was inspired by many languages aside from CL, including Mozart/Oz, AspectJ, and Prolog.
He didn't mean he'd quit out of boredom, he meant he'd quit out of frustration with proglangs that bite you in the ass when writing e.g. concurrent programs
