The Parable of the Bread Knife
I work(ed) in a dining hall (I gave my two week notice on Sunday, so I won't be there much longer. Yay!). One of my job functions is to slice rolls, which I am fairly decent at. The knives available to me are not very sharp, in general. In fact, they are downright dull.
Several weeks ago, I was slicing bread, and commenting on how dull the knives were. I took one and ran it across my hand, inflicting, of course, no wound, in order to demonstrate my point. Several days later, I was cutting bread again, acting as if the knife were dull. I cut my hand, as the knife had just been sharpened. Because of my contempt for the blade, the one time it was actually dangerous, I didn't take proper precautions.
The moral? The knife that is dull lulls one into a false sense of security. The knife that is always sharp teaches one quickly to be aware.