“Investigation of reality is in a way difficult, in a way easy. An indication of this is that no one can attain it in a wholly satisfactory way and that no one misses it completely: each of us says something about nature, and although as an individual we advance the subject little if at all, from all of us taken together something sizeable results — and as the proverb has it, who can miss a barn-door.” (Aristotle, cited in Barnes, 1985:17)