Tattoo… but who?

I go through a tattoo phase every now and then. So far I’ve been lucky enough not to have allowed a temporary feeling to become a permanent regret because these phases never last long enough. This is probably a good thing, as I am the kind of guy who once adamently informed his girlfriend (and thankfully now, lovely wife) that I would name our firstborn girl ‘East’ and our firstborn boy ‘North’. Agonizing.

So anyway… my current urge is to have a sort of Mt. Rushmore done on my shoulder and back with the faces of four thinkers who have influenced me the most. I might work a quote or two into the art as well… It has probably been done before, but I’ve never seen it.

My question for you is this:

If you had to have the words and faces of four great thinkers permanently engraved on your body, who and what would you choose, and why?