Watson asks Holmes why his explanations seem so obvious, yet so out of reach until shared. “I believe that my eyes are as good as yours,” Watson says. “Quite so,” Holmes responds, throwing himself down into an armchair. “You see, but you do not observe.” Holmes then asks him how many steps there are leading up from the hall downstairs. Watson has traversed this staircase hundreds of times. Yet he has no answer. “You have not observed,” Holmes says, triumphant. “And yet you have seen.”
