Put differently, mechanical work has required me to cultivate different intellectual habits. Further, habits of mind have an ethical dimension that we don’t often think about. Good diagnosis requires attentiveness to the machine, almost a conversation with it, rather than assertiveness, as in the position papers produced on K Street. Cognitive psychologists speak of “metacognition,” which is the activity of stepping back and thinking about your own thinking. It is what you do when you stop for a moment in your pursuit of a solution, and wonder whether your understanding of the problem is adequate. The slap of worn-out pistons hitting their cylinders can sound a lot like loose valve tappets, so to be a good mechanic you have to be constantly open to the possibility that you may be mistaken. This is a virtue that is at once cognitive and moral. It seems to develop because the mechanic, if he is the sort who goes on to become good at it, internalizes the healthy functioning of the motorcycle as an object of passionate concern. How else can you explain the elation he gets when he identifies the root cause of some problem?