Aristotle compared the acquisition of knowledge to wax taking on the shape of a seal. I prefer to think of it (and must have gotten this from somewhere--don't know where) to a hand grasping something, with the interior of the hand taking on the shape of that which has been grasped (or perhaps I should say "the surface of the hand" in order to avoid the impression that I am imputing a kind of interiority--I am not sure that I want to go there). This metaphor captures how knowledge, and cognition in general, always involves active and passive aspects,with language being the way we reach out at things that we can't actually touch.
Commentary and discussion regarding science, faith and culture by Leo White