I think the problem with philosophy is that language and words only go this far and we humans get tired fast when just thinking hard inside our heads without any interaction with the external world and no real-world problem to solve. I believe it was the book "The Three Pillars of Zen" that illustrated this effect by comparing the posture of Rodins Thinker [1] with the posture of a meditator [2]. So not only do we run circles around our own concepts that are most likely grounded in the unconscious, but we also get very tired, irritated and depressed from it, that's at least my experience.
[1] http://en.wikipedia.org/wiki/The_Thinker [2] http://www.sacred-texts.com/bud/cob/img/buddha.jpg