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 reflective craftsman Specialized tools like bench shears have proliferated throughout history in part because craftsmen necessarily do the same task with the same tool over and over. After a while, the task becomes routine, and the craftsman is able to perform it with predictable skill. The most creative of artisans is frequently one who, in the midst of routine, pays attention to the details of the work and the tools that effect that work, and so it is that the reflective craftsman develops ideas for new and improved tools in the course of working with those that he perceives to limit his achievement or efficiency. Henry Petroski, The Evolution of Useful Things Eating your own dog food toolsroutineskill