That thinker doesn’t look very comfortable. 
Leaning back in a rocker — now that’s my preferred contemplation pose, knitting needles clacking or netbook keys tapping.

Thinking about thinking, writing about writing, posing quandaries, positing solutions. 
That’s some of what i had in mind when i conceived of this site years ago, in particular with the Ruminations tab. 
To me the term has always had an agreeable association with “a reflective thinker characterized by quiet contemplation” [Free Dictionary].

For obvious linguistic reasons, i recently wondered if there could be a relationship to the thirteenth century Persian poet Rumi. As fitting as that might be, the theory apparently has the lamentable disadvantage of not being rooted in fact.