Which half? One day when I was a junior medical student, a very important Boston surgeon visited the school and delivered a great treatise on a large number of patients who had undergone successful operations for vascular reconstruction. At the end of the lecture, a young student at the back of the room timidly asked, "Do you have any controls?" Well the great surgeon drew himself up to his full height, hit the desk, and said, "Do you mean did I not operate on half of the patients?" The hall grew very quiet then. The voice at the back of the room hesitantly replied, "Yes, that's what I had in mind." Then the visitor's fist really came down as he thundered, "Of course not. That would have doomed half of them to their death!" God, it was quiet then, and one could scarcely hear the small voice ask, "Which half?" E.E. Peacock Jr., Seeing With Fresh Eyes science
The city's most vital organs Streets and their sidewalks, the main public places of a city, are its most vital organs. They serve many purposes besides carrying vehicles, and city sidewalks—the pedestrian parts of the streets—serve many purposes besides carrying pedestrians. These uses are bound up with circulation but are not identical with it and in their own right they are at least as basic as circulation to the proper workings of cities. Jane Jacobs, The Death and Life of Great American Cities The right overlap streets