"Well you see," Roshi replied, "for most people, and especially for most educated people like you and I, what we perceive and experience is heavily mediated, through language and concepts that are deeply ingrained in our ways of thinking and feeling. Our objective here is to induce in ourselves and in each other a psychological state that involves the unmediated experience of the world, because we believe that that state has certain desirable properties. It's impossible in general to reach that state through any particular form or method, since forms and methods are themselves examples of the mediators that we are trying to avoid. So we employ a variety of ad hoc means, some linguistic like koans and some non-linguistic like zazen, in hopes that for any given student one or more of our methods will, in whatever way, engender the condition of non-mediated experience that is our goal. And since even thinking in terms of mediators and goals tends to reinforce our undesirable dependency on concepts, we actively discourage exactly this kind of analytical discourse."
And the student was enlightened.
(from David Chess apparently, via darkstar on MeFi)