I've talked to a lot of people about how they got into Clojure, and a fair number credit Paul Graham's essays for selling them on the idea of using a Lisp. I think there's a pretty clear causal link.
For me it was reading SICP which used LISP (scheme) that made me pay attention to clojure.
Clojure did emerge in the right time, it maybe all corelated, maybe Hickey felt a lisp revival coming when pg wrote his essays and decided to build the one he always wanted. That's a question I'd ask him if I could.
So now pg is not only responsible for Clojure's success, he's the reason it exists in the first place? As a lisp, anyway? This is getting pretty ridiculous, here.
I shouldn't have used 'when', it can be read as an implication, but I just meant around the time pg talked about lisp.