One of the smartest guys I've worked with, and an excellent boss. I tried emulating his ability to think hard before replying, but my brain doesn't work like that. I make intuitive leaps to an answer that I have very little rational path to and then find it incredibly hard to shift from that answer (or expand on it).
I can think hard on things, but I need peace, quiet, and preferably to be walking near trees, to do it. And my thinking process is about making lots of intuitive leaps and then filtering them, rather than rationally deducting a train of thought.
Brains are fascinating.
edit: also an INTP, verging on ENTP as I get older